File: CH2.xml

package info (click to toggle)
libxaw 2%3A1.0.13-1.1
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, sid
  • size: 4,396 kB
  • sloc: ansic: 37,290; xml: 19,657; sh: 11,262; makefile: 297
file content (1892 lines) | stat: -rw-r--r-- 58,540 bytes parent folder | download | duplicates (4)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
<chapter><title>Using Widgets</title>
<sect1 id='Using_Widgets'>
<title>Using Widgets</title>
<para>
Widgets serve as the primary tools for building a user interface or
application environment.  The Athena widget set consists of primitive
widgets that contain no children (for example, a command button) and
composite widgets which may contain one or more widget children (for
example, a Box widget).
</para>
<para>
The remaining chapters explain the widgets that are provided
by the Athena widget set.
These user-interface components serve as an interface for
application programmers who do not want to implement their own widgets.
In addition, they serve as a starting point
for those widget programmers who, using the Intrinsics mechanisms,
want to implement alternative application programming interfaces.
</para>
<para>
This chapter is a brief introduction to widget programming.  The
examples provided use the Athena widgets, though most of the concepts
will apply to all widget sets.  Although there are several programming
interfaces to the X Toolkit, only one is described here.  A full
description of the programming interface is provided in the document
<emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>.
</para>
<sect2 id="Setting_the_Locale">
<title>Setting the Locale</title>
<para>
<!-- .LP -->
<!-- .XS -->
<!-- 	Setting the Locale -->
<!-- .XE -->
If it is desirable that the application take advantage of
internationalization (i18n), you must establish locale with
<function>XtSetLanguageProc</function>
before <function>XtDisplayInitialize</function> or <xref linkend='XtAppInitialize' xrefstyle='select: title'/>
is called.  For full details, please refer to the document
<emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>, section 2.2. However, the following simplest-case
call is sufficient in many or most applications.
</para>
<para>
<!-- .LP -->
<!-- .IN "internationalization" "" "" -->
<!-- .IN "XtSetLanguageProc" "" "@DEF@" -->
<!-- .IN "locale" "" "" -->
<literallayout class="monospaced">
<!-- .TA .5i 2i -->
<!-- .ta .5i 2i -->
	XtSetLanguageProc(NULL, NULL, NULL);
</literallayout>
</para>
<para>
<!-- .LP -->
Most notably, this will affect the Standard C locale, determine which
resource files will be loaded, and what fonts will be required of FontSet
specifications.  In many cases, the addition of this line is the only source change
required to internationalize Xaw programs, and will not disturb the function
of programs in the default "C" locale.
</para>
</sect2>
<sect2 id="Initializing_the_Toolkit">
<title>Initializing the Toolkit</title>
<para>
<!-- .LP -->
<!-- .XS -->
<!-- 	Initializing the Toolkit -->
<!-- .XE -->
You must call a toolkit initialization function before invoking any
other toolkit routines (besides locale setting, above).
<xref linkend='XtAppInitialize' xrefstyle='select: title'/>
opens the X server connection, parses the command line,
and creates an initial widget that will serve as the root of
a tree of widgets created by this application.
<!-- .IN "initialization" "" "@DEF@" -->
<!-- .IN "toolkit initialization" "" "@DEF@" -->
<!-- .IN "XtAppInitialize" "" "@DEF@" -->
<!-- .IN "fallback resources" "" "@DEF@" -->
<funcsynopsis id='XtAppInitialize'>
<funcprototype>
  <funcdef>Widget<function> XtAppInitialize</function></funcdef>
  <paramdef>XtAppContext<parameter> app_context_return</parameter></paramdef>
  <paramdef>String<parameter> application_class</parameter></paramdef>
  <paramdef>XrmOptionDescRec<parameter> options</parameter></paramdef>
  <paramdef>Cardinal<parameter> num_options</parameter></paramdef>
  <paramdef>int<parameter> *argc_in_out</parameter></paramdef>
  <paramdef>String<parameter> *argv_in_out</parameter></paramdef>
  <paramdef>String<parameter> *fallback_resources</parameter></paramdef>
  <paramdef>ArgList<parameter> args</parameter></paramdef>
  <paramdef>Cardinal<parameter> num_args</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>app_con_return</emphasis>
    </term>
    <listitem>
      <para>
Returns the application context of this application, if non-NULL.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>application_class</emphasis>
    </term>
    <listitem>
      <para>
Specifies the class name of this application,
which is usually the generic name for all instances of this application.
A useful convention is to form the class name by capitalizing the
first letter of the application name. For example, the application named
``xman'' has a class name of ``Xman''.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>options</emphasis>
    </term>
    <listitem>
      <para>
Specifies how to parse the command line for any application-specific
resources.
The options argument is passed as a parameter to
<olink targetdoc='libX11' targetptr='XrmParseCommand'><function>XrmParseCommand</function></olink>.
For further information,
see <emphasis remap='I'>Xlib - C Language Interface</emphasis>.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>num_options</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of entries in the options list.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>argc_in_out</emphasis>
    </term>
    <listitem>
      <para>
Specifies a pointer to the number of command line parameters.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>argv_in_out</emphasis>
    </term>
    <listitem>
      <para>
Specifies the command line parameters.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>fallback_resources</emphasis>
    </term>
    <listitem>
      <para>
Specifies resource values to be used if the site-wide application class
defaults file cannot be opened, or NULL.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>args</emphasis>
    </term>
    <listitem>
      <para>
Specifies the argument list to use when creating the Application shell.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>num_args</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of arguments in <emphasis remap='I'>args</emphasis>.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
This function will remove the command line arguments that the toolkit
reads from <emphasis remap='I'>argc_in_out</emphasis>, and <emphasis remap='I'>argv_in_out</emphasis>.  It will then
attempt to open the display.  If the display cannot be opened, an error
message is issued and XtAppInitialize terminates the application.  Once
the display is opened, all resources are read from the locations
specified by the Intrinsics.  This function returns an ApplicationShell
widget to be used as the root of the application's widget tree.
</para>
</sect2>
<sect2 id="Creating_a_Widget">
<title>Creating a Widget</title>
<para>
<!-- .LP -->
<!-- .XS -->
<!-- 	Creating a Widget -->
<!-- .XE -->
<!-- .IN "widget creation" "" "@DEF@" -->
<!-- .IN "creating widgets" "" "@DEF@" -->
<!-- .IN "XtRealizeWidget" "" "" -->
Creating a widget is a three-step process.  First, the widget instance
is allocated, and various instance-specific attributes are set by
using <function>XtCreateWidget</function>.  Second, the widget's parent is informed
of the new child by using <function>XtManageChild</function>.  Finally, X windows are
created for the parent and all its children by using <xref linkend='XtRealizeWidget' xrefstyle='select: title'/>
and specifying the top-most widget. The first two steps can be
combined by using <xref linkend='XtCreateManagedWidget' xrefstyle='select: title'/>.  In addition,
<xref linkend='XtRealizeWidget' xrefstyle='select: title'/> is automatically called when the child becomes
managed if the parent is already realized.
</para>
<para>
<!-- .LP -->
To allocate, initialize, and manage a widget, use
<function>XtCreateManagedWidget .</function>
<!-- .IN "XtCreateManagedWidget" "" "@DEF@" -->
<funcsynopsis id='XtCreateManagedWidget'>
<funcprototype>
  <funcdef>Widget<function> XtCreateManagedWidget</function></funcdef>
  <paramdef>String<parameter> name</parameter></paramdef>
  <paramdef>WidgetClass<parameter> widget_class</parameter></paramdef>
  <paramdef>Widget<parameter> parent</parameter></paramdef>
  <paramdef>ArgList<parameter> args</parameter></paramdef>
  <paramdef>Cardinal<parameter> num_args</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>name</emphasis>
    </term>
    <listitem>
      <para>
Specifies the instance name for the created widget that is used for retrieving
widget resources.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>widget_class</emphasis>
    </term>
    <listitem>
      <para>
Specifies the widget class pointer for the created widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>parent</emphasis>
    </term>
    <listitem>
      <para>
Specifies the parent widget ID.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>args</emphasis>
    </term>
    <listitem>
      <para>
Specifies the argument list.  The argument list is a variable-length
list composed of name and value pairs that contain information
pertaining to the specific widget instance being created.  For further
information, see Section 2.7.2. <!-- xref> -->
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>num_args</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of arguments in the argument list.
If the num_args is zero, the argument list is never referenced.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
When a widget instance is successfully created, the widget identifier
is returned to the application.  If an error is encountered, the
<function>XtError</function>
routine is invoked to inform the user of the error.
<!-- .IN "XtError" "" "" -->
</para>
<para>
<!-- .LP -->
For further information, see <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>.
</para>
</sect2>
<sect2 id="Common_Resources">
<title>Common Resources</title>
<!-- .XS -->
<!-- 	Common Resources -->
<!-- .XE -->
<!-- .IN "resource" "" -->
<para>
<!-- .LP -->
Although a widget can have unique arguments that it understands, all
widgets have common arguments that provide some regularity of operation.
The common arguments allow arbitrary widgets to be managed by
higher-level components without regard for the individual widget type.
Widgets will ignore any argument that they do not understand.
</para>
<para>
<!-- .LP -->
The following resources are retrieved from the argument list
or from the resource database by all of the Athena widgets:
<informaltable>
  <tgroup cols='4' align='center'>
  <colspec colname='c1'/>
  <colspec colname='c2'/>
  <colspec colname='c3'/>
  <colspec colname='c4'/>
  <thead>
    <row>
      <entry>Name</entry>
      <entry>Class</entry>
      <entry>Type</entry>
      <entry>Default Value</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>accelerators</entry>
      <entry>Accelerators</entry>
      <entry>AcceleratorTable</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>ancestorSensitive</entry>
      <entry>AncestorSensitive</entry>
      <entry>Boolean</entry>
      <entry>True</entry>
    </row>
    <row>
      <entry>background</entry>
      <entry>Background</entry>
      <entry>Pixel</entry>
      <entry>XtDefaultBackground</entry>
    </row>
    <row>
      <entry>backgroundPixmap</entry>
      <entry>Pixmap</entry>
      <entry>Pixmap</entry>
      <entry>XtUnspecifiedPixmap</entry>
    </row>
    <row>
      <entry>borderColor</entry>
      <entry>BorderColor</entry>
      <entry>Pixel</entry>
      <entry>XtDefaultForeground</entry>
    </row>
    <row>
      <entry>borderPixmap</entry>
      <entry>Pixmap</entry>
      <entry>Pixmap</entry>
      <entry>XtUnspecifiedPixmap</entry>
    </row>
    <row>
      <entry>borderWidth</entry>
      <entry>BorderWidth</entry>
      <entry>Dimension</entry>
      <entry>1</entry>
    </row>
    <row>
      <entry>colormap</entry>
      <entry>Colormap</entry>
      <entry>Colormap</entry>
      <entry>Parent's Colormap</entry>
    </row>
    <row>
      <entry>depth</entry>
      <entry>Depth</entry>
      <entry>int</entry>
      <entry>Parent's Depth</entry>
    </row>
    <row>
      <entry>destroyCallback</entry>
      <entry>Callback</entry>
      <entry>XtCallbackList</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>height</entry>
      <entry>Height</entry>
      <entry>Dimension</entry>
      <entry><emphasis remap='I'>widget dependent</emphasis></entry>
    </row>
    <row>
      <entry>mappedWhenManaged</entry>
      <entry>MappedWhenManaged</entry>
      <entry>Boolean</entry>
      <entry>True</entry>
    </row>
    <row>
      <entry>screen</entry>
      <entry>Screen</entry>
      <entry>Screen</entry>
      <entry>Parent's Screen</entry>
    </row>
    <row>
      <entry>sensitive</entry>
      <entry>Sensitive</entry>
      <entry>Boolean</entry>
      <entry>True</entry>
    </row>
    <row>
      <entry>translations</entry>
      <entry>Translations</entry>
      <entry>TranslationTable</entry>
      <entry><emphasis remap='I'>widget dependent</emphasis></entry>
    </row>
    <row>
      <entry>width</entry>
      <entry>Width</entry>
      <entry>Dimension</entry>
      <entry><emphasis remap='I'>widget dependent</emphasis></entry>
    </row>
    <row>
      <entry>x</entry>
      <entry>Position</entry>
      <entry>Position</entry>
      <entry>0</entry>
    </row>
    <row>
      <entry>y</entry>
      <entry>Position</entry>
      <entry>Position</entry>
      <entry>0</entry>
    </row>
  </tbody>
  </tgroup>
</informaltable>
<!-- .IN "XtDefaultForeground" "" "" -->
<!-- .IN "XtDefaultBackground" "" "" -->
</para>
<para>
<!-- .LP -->
The following additional resources are retrieved from the argument list
or from the resource database by many of the Athena widgets:
<informaltable>
  <tgroup cols='4' align='center'>
  <colspec colname='c1'/>
  <colspec colname='c2'/>
  <colspec colname='c3'/>
  <colspec colname='c4'/>
  <thead>
    <row>
      <entry>Name</entry>
      <entry>Class</entry>
      <entry>Type</entry>
      <entry>Default Value</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>callback</entry>
      <entry>Callback</entry>
      <entry>XtCallbackList</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>cursor</entry>
      <entry>Cursor</entry>
      <entry>Cursor</entry>
      <entry><emphasis remap='I'>widget dependent</emphasis></entry>
    </row>
    <row>
      <entry>foreground</entry>
      <entry>Foreground</entry>
      <entry>Pixel</entry>
      <entry>XtDefaultForeground</entry>
    </row>
    <row>
      <entry>insensitiveBorder</entry>
      <entry>Insensitive</entry>
      <entry>Pixmap</entry>
      <entry>GreyPixmap</entry>
    </row>
  </tbody>
  </tgroup>
</informaltable>
<!-- .IN "XtDefaultForeground" "" "" -->
</para>
</sect2>
<sect2 id="Resource_Conversions">
<title>Resource Conversions</title>
<!-- .XS -->
<!-- 	Resource Conversions -->
<!-- .XE -->
<!-- .IN "conversions" "" "@DEF@" -->
<!-- .IN "string conversions" "" "@DEF@" -->
<!-- .IN "type conversions" "" "@DEF@" -->
<para>
<!-- .LP -->
Most resources in the Athena widget set have a converter registered that
will translate the string in a resource file to the correct internal
representation.  While some are obvious (string to integer, for example),
others need specific mention of the allowable values.  Three general
converters are described here:
</para>
<itemizedlist>
  <listitem>
    <para>
Cursor
    </para>
  </listitem>
  <listitem>
    <para>
Pixel
    </para>
  </listitem>
  <listitem>
    <para>
Bitmap
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
Many widgets have defined special converters that apply only to that
widget.  When these occur, the documentation section for that widget
will describe the converter.
</para>
<sect3 id="Cursor_Conversion">
<title>Cursor Conversion</title>
<!-- .IN "conversions" "ColorCursor" "@DEF@" -->
<!-- .IN "conversions" "Cursor" "@DEF@" -->
<!-- .IN "cursor" "" "" -->
<para>
<!-- .LP -->
The value for the <function>cursorName</function> resource is specified in the resource
database as a string, and is of the following forms:
</para>
<itemizedlist>
  <listitem>
    <para>
A standard X cursor name from <function>&lt; X11/cursorfont.h &gt;</function>.
The names in <function>cursorfont.h</function> each describe a specific cursor.  The
resource names for these cursors are exactly like the names in this file
except the <function>XC_</function> is not used.  The cursor definition <function>XC_gumby</function>
has a resource name of <function>gumby</function>.
    </para>
  </listitem>
  <listitem>
    <para>
Glyphs, as in <emphasis remap='I'>FONT font-name glyph-index [[ font-name ] glyph-index ]</emphasis>.
The first font and glyph specify the cursor source pixmap.
The second font and glyph specify the cursor mask pixmap.
The mask font defaults to the source font,
and the mask glyph index defaults to the source glyph index.
    </para>
  </listitem>
  <listitem>
    <para>
A relative or absolute file name.
If a relative or absolute file name is specified, that file is used to
create the source pixmap.  Then the string "Mask" is appended to
locate the cursor mask pixmap.  If the "Mask" file does not exist, the
suffix "msk" is tried.  If "msk" fails, no cursor mask will be used.
If the filename does not start with '/' or './' the the bitmap
file path is used (see section 2.4.3). <!-- xref -->
    </para>
  </listitem>
</itemizedlist>
</sect3>
<sect3 id="Pixel_Conversion">
<title>Pixel Conversion</title>
<para>
<!-- .LP -->
<!-- .IN "conversions" "Pixel" "@DEF@" -->
<!-- .IN "pixel" "" "" -->
<!-- .IN "rgb.txt" "" "" -->
<!-- .IN "XtDefaultForeground" "" "" -->
<!-- .IN "XtDefaultBackground" "" "" -->
The string-to-pixel converter takes any name that is acceptable to
XParseColor (see <emphasis remap='I'>Xlib - C Language Interface</emphasis>).  In addition this routine understands
the special toolkit symbols `XtDefaultForeground' and
`XtDefaultBackground', described in <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>.  In short the acceptable
pixel names are:
</para>
<itemizedlist>
  <listitem>
    <para>
Any color name for the rgb.txt file (typically in the directory
/usr/lib/X11 on POSIX systems).
    </para>
  </listitem>
  <listitem>
    <para>
A numeric specification of the form #&lt;red&gt;&lt;green&gt;&lt;blue&gt; where these
numeric values are hexadecimal digits (both upper and lower case).
    </para>
  </listitem>
  <listitem>
    <para>
The special strings `XtDefaultForeground' and `XtDefaultBackground'
    </para>
  </listitem>
</itemizedlist>
</sect3>
<sect3 id="Bitmap_Conversion">
<title>Bitmap Conversion</title>
<!-- .IN "bitmap conversions" "" "@DEF@" -->
<!-- .IN "conversions" "Bitmap" "@DEF@" -->
<!-- .IN "bitmapFilePath" "" "@DEF@" -->
<!-- .IN "BitmapFilePath" "" "@DEF@" -->
<!-- .IN "/usr/include/X11/bitmaps" "" "" -->
<para>
<!-- .LP -->
The string-to-bitmap converter attempts to locate a file containing
bitmap data whose name is specified by the input string.  If the file
name is relative (i.e. does not begin with / or ./), the directories to
be searched are specified in the <function>bitmapFilePath</function> resource--class
<function>BitmapFilePath</function>.  This resource specifies a colon (:) separated
list of directories that will be searched for the named bitmap or
cursor glyph (see section 2.4.1).  The <function>bitmapFilePath</function> resource is
global to the application, and may <function>not</function> be specified differently
for each widget that wishes to convert a cursor to bitmap.  In addition
to the directories specified in the <function>bitmapFilePath</function> resource a
default directory is searched.  When using POSIX the default
directory is
<function>/usr/include/X11/bitmaps .</function>
</para>
</sect3>
</sect2>
<sect2 id="Realizing_a_Widget">
<title>Realizing a Widget</title>
<para>
<!-- .LP -->
<!-- .XS -->
<!-- 	Realizing a Widget -->
<!-- .XE -->
<!-- .IN "realizing widgets" "" "@DEF@" -->
The
<xref linkend='XtRealizeWidget' xrefstyle='select: title'/>
function performs two tasks:
</para>
<itemizedlist>
  <listitem>
    <para>
Calculates the geometry constraints of all managed descendants
of this widget.  The actual calculation is put off until realize time
for performance reasons.
    </para>
  </listitem>
  <listitem>
    <para>
Creates an X window for the widget and, if it is a composite widget,
realizes each of its managed children.
<!-- .IN "XtRealizeWidget" "" "@DEF@" -->
<funcsynopsis id='XtRealizeWidget'>
<funcprototype>
  <funcdef>void<function> XtRealizeWidget</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
    </para>
  </listitem>
  <listitem>
    <para>
Specifies the widget.
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
For further information about this function,
see the <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>.
</para>
</sect2>
<sect2 id="Processing_Events">
<title>Processing Events</title>
<para>
<!-- .LP -->
<!-- .XS -->
<!-- 	Processing Events -->
<!-- .XE -->
<!-- .IN "events" "" "" -->
<!-- .IN "XtAppInitialize" "" "" -->
Now that the application has created, managed and realized its
widgets, it is ready to process the events that will be delivered by the
X Server to this client.  A function call that will process the
events is <xref linkend='XtAppMainLoop' xrefstyle='select: title'/>.
<!-- .IN "XtAppMainLoop" "" "@DEF@" -->
<funcsynopsis id='XtAppMainLoop'>
<funcprototype>
  <funcdef>void<function> XtAppMainLoop</function></funcdef>
  <paramdef>XtAppContext<parameter> app_context</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>app_context</emphasis>
    </term>
    <listitem>
      <para>
Specifies the application context of this application.  The value is
normally returned by <xref linkend='XtAppInitialize' xrefstyle='select: title'/>.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
This function never returns: it is an infinite loop that processes the
X events.  User input can be handled through callback procedures and
application defined action routines.  More details are provided in
<emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>.
</para>
</sect2>
<sect2 id="Standard_Widget_Manipulation_Functions">
<title>Standard Widget Manipulation Functions</title>
<!-- .XS -->
<!-- 	Standard Widget Manipulation Functions -->
<!-- .XE -->
<para>
<!-- .LP -->
After a widget has been created, a client can interact with that
widget by calling one of the standard widget manipulation routines
provided by the Intrinsics, or a widget class-specific manipulation routine.
</para>
<para>
<!-- .LP -->
The Intrinsics provide generic routines to give the application programmer
access to a set of standard widget functions.  The common widget
routines let an application or composite widget perform the following
operations on widgets without requiring explicit knowledge of the widget
type.
</para>
<itemizedlist>
  <listitem>
    <para>
Control the mapping of widget windows
    </para>
  </listitem>
  <listitem>
    <para>
Destroy a widget instance
    </para>
  </listitem>
  <listitem>
    <para>
Obtain an argument value
    </para>
  </listitem>
  <listitem>
    <para>
Set an argument value
    </para>
  </listitem>
</itemizedlist>
<sect3 id="Mapping_Widgets">
<title>Mapping Widgets</title>
<para>
<!-- .LP -->
By default,
widget windows are mapped (made viewable) automatically by
<xref linkend='XtRealizeWidget' xrefstyle='select: title'/>.  This behavior can be disabled by using
<xref linkend='XtSetMappedWhenManaged' xrefstyle='select: title'/>, making the client responsible for calling
<xref linkend='XtMapWidget' xrefstyle='select: title'/> to make the widget viewable.
<!-- .IN "XtSetMappedWhenManaged" "" "@DEF@" -->
<!-- .IN "XtMapWidget" "" "" -->
<!-- .IN "XtRealizeWidget" "" "" -->
<funcsynopsis id='XtSetMappedWhenManaged'>
<funcprototype>
  <funcdef>void<function> XtSetMappedWhenManaged</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
  <paramdef>Boolean<parameter> map_when_managed</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>map_when_managed</emphasis>
    </term>
    <listitem>
      <para>
Specifies the new value.
If map_when_managed is <function>True</function>, the widget is mapped automatically
when it is realized.  If map_when_managed is <function>False</function>, the client
must call
<xref linkend='XtMapWidget' xrefstyle='select: title'/>
or make a second call to
<xref linkend='XtSetMappedWhenManaged' xrefstyle='select: title'/>
to cause the child window to be mapped.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .sp -->
The definition for
<xref linkend='XtMapWidget' xrefstyle='select: title'/>
is:
<!-- .IN "XtMapWidget" "" "@DEF@" -->
<funcsynopsis id='XtMapWidget'>
<funcprototype>
  <funcdef>void<function> XtMapWidget</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the widget.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
When you are creating several children in sequence for a previously
realized common parent it is generally more efficient to construct a
list of children as they are created (using <function>XtCreateWidget</function>) and
then use <xref linkend='XtManageChildren' xrefstyle='select: title'/> to request that their parent managed
them all at once.  By managing a list of children at one time, the
parent can avoid wasteful duplication of geometry processing and the
associated ``screen flash''.
<!-- .IN "XtManageChildren" "" "@DEF@" -->
<!-- .IN "XtCreateWidget" "" "" -->
<funcsynopsis id='XtManageChildren'>
<funcprototype>
  <funcdef>void<function> XtManageChildren</function></funcdef>
  <paramdef>WidgetList<parameter> children</parameter></paramdef>
  <paramdef>Cardinal<parameter> num_children</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>children</emphasis>
    </term>
    <listitem>
      <para>
Specifies a list of children to add.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>num_children</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of children to add.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
If the parent is already visible on the screen, it is especially
important to batch updates so that the minimum amount of visible window
reconfiguration is performed.
</para>
<para>
<!-- .LP -->
For further information about these functions,
see the <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>.
</para>
</sect3>
<sect3 id="Destroying_Widgets">
<title>Destroying Widgets</title>
<para>
<!-- .LP -->
To destroy a widget instance of any type, use
<xref linkend='XtDestroyWidget' xrefstyle='select: title'/>
<!-- .IN "XtDestroyWidget" "" "@DEF@" -->
<funcsynopsis id='XtDestroyWidget'>
<funcprototype>
  <funcdef>void<function> XtDestroyWidget</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the widget.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<xref linkend='XtDestroyWidget' xrefstyle='select: title'/>
destroys the widget and recursively destroys any children that it may have,
including the windows created by its children.
After calling
<function>XtDestroyWidget ,</function>
no further references should be made to the widget or any children
that the destroyed widget may have had.
</para>
</sect3>
<sect3 id="Retrieving_Widget_Resource_Values">
<title>Retrieving Widget Resource Values</title>
<para>
<!-- .LP -->
To retrieve the current value of a resource attribute associated
with a widget instance, use
<function>XtGetValues .</function>
<!-- .IN "XtGetValues" "" "@DEF@" -->
<funcsynopsis id='XtGetValues'>
<funcprototype>
  <funcdef>void<function> XtGetValues</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
  <paramdef>ArgList<parameter> args</parameter></paramdef>
  <paramdef>Cardinal<parameter> num_args</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>args</emphasis>
    </term>
    <listitem>
      <para>
Specifies a variable-length argument list of name and <function>address</function>
pairs that contain the resource name and the address into which the
resource value is stored.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>num_args</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of arguments in the argument list.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
The arguments and values passed in the argument list are dependent on
the widget. Note that the caller is responsible for providing space
into which the returned resource value is copied; the <function>ArgList</function>
contains a pointer to this storage (e.g. x and y must be
allocated as Position).  For further information, see the <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>.
</para>
</sect3>
<sect3 id="Modifying_Widget_Resource_Values">
<title>Modifying Widget Resource Values</title>
<para>
<!-- .LP -->
To modify the current value of a resource attribute associated with a
widget instance, use
<function>XtSetValues .</function>
<!-- .IN "XtSetValues" "" "@DEF@" -->
<funcsynopsis id='XtSetValues'>
<funcprototype>
  <funcdef>void<function> XtSetValues</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
  <paramdef>ArgList<parameter> args</parameter></paramdef>
  <paramdef>Cardinal<parameter> num_args</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>args</emphasis>
    </term>
    <listitem>
      <para>
Specifies an array of name and <function>value</function> pairs that contain the
arguments to be modified and their new values.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>num_args</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of arguments in the argument list.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
The arguments and values that are passed will depend on the widget
being modified.  Some widgets may not allow certain resources to be
modified after the widget instance has been created or realized.
No notification is given if any part of a <xref linkend='XtSetValues' xrefstyle='select: title'/> request is
ignored.
</para>
<para>
<!-- .LP -->
For further information about these functions, see the <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>.
<!-- .IN "XtGetValues" "" "" -->
<!-- .IN "XtSetValues" "" "" -->
<!-- .NT -->
The argument list entry for
<xref linkend='XtGetValues' xrefstyle='select: title'/>
specifies the address to which the caller wants the value copied.  The
argument list entry for
<function>XtSetValues ,</function>
however, contains the new value itself, if the size of value is less than
sizeof(XtArgVal) (architecture dependent, but at least sizeof(long));
otherwise, it is a pointer to the value.  String resources are always
passed as pointers, regardless of the length of the string.
<!-- .NE -->
</para>
</sect3>
</sect2>
<sect2 id="Using_the_Client_Callback_Interface">
<title>Using the Client Callback Interface</title>
<para>
<!-- .LP -->
<!-- .XS -->
<!-- 	Using the Client Callback Interface -->
<!-- .XE -->
<!-- .IN "callbacks" "" "" -->
Widgets can communicate changes in their state to their clients
by means of a callback facility.
The format for a client's callback handler is:
<!-- .IN "CallbackProc" "" "@DEF@" -->
<funcsynopsis id='CallbackProc'>
<funcprototype>
  <funcdef>void<function> CallbackProc</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
  <paramdef>XtPointer<parameter> client_data</parameter></paramdef>
  <paramdef>XtPointer<parameter> call_data</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies widget for which the callback is registered.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>client_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies arbitrary client-supplied data that the widget should pass
back to the client when the widget executes the client's callback
procedure.  This is a way for the client registering the callback to
also register client-specific data: a pointer to additional information
about the widget, a reason for invoking the callback, and so on. If no
additional information is necessary, NULL may be passed as this argument.
This field is also frequently known as the <emphasis remap='I'>closure</emphasis>.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>call_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies any callback-specific data the widget wants to pass to the client.
For example, when Scrollbar executes its <function>jumpProc</function> callback list,
it passes the current position of the thumb in <emphasis remap='I'>call_data</emphasis>.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
Callbacks can be registered either by creating an argument containing
the callback list described below or by using the special convenience
routines <xref linkend='XtAddCallback' xrefstyle='select: title'/> and <function>XtAddCallbacks</function>.  When the widget
is created, a pointer to a list of callback procedure and data pairs can
be passed in the argument list to
<function>XtCreateWidget .</function>
The list is of type
<function>XtCallbackList :</function>
<!-- .IN "XtCallbackProc" -->
<!-- .IN "XtAddCallbacks" -->
<!-- .IN "XtAddCallback" -->
<!-- .IN "XtCallbackList" "" "@DEF@" -->
<!-- .IN "XtCallbackRec" "" "@DEF@" -->
</para>
<para>
<!-- .LP -->
<literallayout class="monospaced">
<!-- .TA .5i 3i -->
<!-- .ta .5i 3i -->
typedef struct {
	XtCallbackProc callback;
	XtPointer closure;
} XtCallbackRec, *XtCallbackList;
</literallayout>
</para>
<para>
<!-- .LP -->
The callback list must be allocated and initialized before calling
<function>XtCreateWidget .</function>
<!-- .IN "XtCreateWidget" -->
The end of the list is identified by an entry containing NULL in
callback and closure.  Once the widget is created, the client can change
or de-allocate this list; the widget itself makes no further reference
to it.  The closure field contains the client_data passed to the
callback when the callback list is executed.
</para>
<para>
<!-- .LP -->
The second method for registering callbacks is to use
<xref linkend='XtAddCallback' xrefstyle='select: title'/>
after the widget has been created.
<!-- .IN "XtAddCallback" "" "@DEF@" -->
<funcsynopsis id='XtAddCallback'>
<funcprototype>
  <funcdef>void<function> XtAddCallback</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
  <paramdef>String<parameter> callback_name</parameter></paramdef>
  <paramdef>XtCallbackProc<parameter> callback</parameter></paramdef>
  <paramdef>XtPointer<parameter> client_data</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the widget to add the callback to.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>callback_name</emphasis>
    </term>
    <listitem>
      <para>
Specifies the callback list within the widget to append to.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>callback</emphasis>
    </term>
    <listitem>
      <para>
Specifies the callback procedure to add.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>client_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the data to be passed to the callback when it is invoked.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<xref linkend='XtAddCallback' xrefstyle='select: title'/>
adds the specified callback to the list for the named widget.
</para>
<para>
<!-- .LP -->
All widgets provide a callback list named
<function>destroyCallback</function>
<!-- .IN "destroyCallback" "" "@DEF@" -->
where clients can register procedures that are to be executed when the
widget is destroyed.  The destroy callbacks are executed when the widget
or an ancestor is destroyed.  The <emphasis remap='I'>call_data</emphasis> argument is unused for
destroy callbacks.
</para>
</sect2>
<sect2 id="Programming_Considerations">
<title>Programming Considerations</title>
<para>
<!-- .LP -->
<!-- .XS -->
<!-- 	Programming Considerations -->
<!-- .XE -->
This section provides some guidelines on how to set up an application
program that uses the X Toolkit.
</para>
<sect3 id="Writing_Applications">
<title>Writing Applications</title>
<para>
<!-- .LP -->
<!-- .IN "writing applications" -->
<!-- .IN "StringDefs.h" -->
<!-- .IN "Intrinsic.h" -->
When writing an application that uses the X Toolkit,
you should make sure that your application performs the following:
</para>
<orderedlist>
  <listitem>
    <para>
Include
<function>&lt; X11/Intrinsic.h &gt;</function>
in your application programs.
This header file automatically includes
<function>&lt; X11/Xlib.h &gt;,</function>
so all Xlib functions also are defined.
It may also be necessary to include <function>&lt; X11/StringDefs.h &gt;</function> when setting
up argument lists, as many of the XtN<emphasis remap='I'>something</emphasis> definitions are
only defined in this file.
    </para>
  </listitem>
  <listitem>
    <para>
Include the widget-specific header files for each widget type
that you need to use.
For example,
<function>&lt; X11/Xaw/Label.h &gt;</function>
and
<function>&lt; X11/Xaw/Command.h &gt;.</function>
    </para>
  </listitem>
  <listitem>
    <para>
Call the
<xref linkend='XtAppInitialize' xrefstyle='select: title'/>
<!-- .IN "XtAppInitialize" -->
function before invoking any other toolkit or Xlib functions.
For further information,
see Section 2.1 and the <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>.
    </para>
  </listitem>
  <listitem>
    <para>
To pass attributes to the widget creation routines that will override
any site or user customizations, set up argument lists.  In this
document, a list of valid argument names is provided in the discussion
of each widget.  The names each have a global symbol defined that begins
with <function>XtN</function> to help catch spelling errors.  For example,
<function>XtNlabel</function> is defined for the <function>label</function> resource of many widgets.
<!-- .IN "XtN" "" "@DEF@" -->
    </para>
  </listitem>
  <listitem>
    <para>
For further information, see Section 2.9.2.2.  <!-- xref -->
    </para>
  </listitem>
  <listitem>
    <para>
When the argument list is set up, create the widget with the
<xref linkend='XtCreateManagedWidget' xrefstyle='select: title'/> function.  For further information, see
Section 2.2 and the <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>.
<!-- .IN "XtCreateManagedWidget" -->
    </para>
  </listitem>
  <listitem>
    <para>
If the widget has any callback routines, set by the
<function>XtNcallback</function>
argument or the
<xref linkend='XtAddCallback' xrefstyle='select: title'/>
function, declare these routines within the application.
<!-- .IN "XtAddCallback" -->
    </para>
  </listitem>
  <listitem>
    <para>
After creating the initial widget hierarchy, windows must be created
for each widget by calling
<xref linkend='XtRealizeWidget' xrefstyle='select: title'/>
on the top level widget.
<!-- .IN "XtRealizeWidget" -->
    </para>
  </listitem>
  <listitem>
    <para>
Most applications now sit in a loop processing events using
<function>XtAppMainLoop ,</function>
for example:
<!-- .IN "XtAppMainLoop" -->
    </para>
  </listitem>
  <listitem>
    <para>
<literallayout class="monospaced">
XtCreateManagedWidget(<emphasis remap='I'>name</emphasis>, <emphasis remap='I'>class</emphasis>, <emphasis remap='I'>parent</emphasis>, <emphasis remap='I'>args</emphasis>, <emphasis remap='I'>num_args</emphasis>);
XtRealizeWidget(<emphasis remap='I'>shell</emphasis>);
XtAppMainLoop(<emphasis remap='I'>app_context</emphasis>);
</literallayout>
    </para>
  </listitem>
  <listitem>
    <para>
For information about this function, see the <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>.
    </para>
  </listitem>
  <listitem>
    <para>
Link your application with
<function>libXaw</function>
(the Athena widgets),
<function>libXmu</function>
(miscellaneous utilities),
<function>libXt</function>
(the X Toolkit Intrinsics),
<function>libSM</function>
(Session Management),
<function>libICE</function>
(Inter-Client Exchange),
<function>libXext</function>
(the extension library needed for the shape extension code which allows
rounded Command buttons), and
<function>libX11</function>
(the core X library).
The following provides a sample command line:
<!-- .IN "libXaw" -->
<!-- .IN "libXmu" -->
<!-- .IN "libXt" -->
<!-- .IN "libSM" -->
<!-- .IN "libICE" -->
<!-- .IN "libXext" -->
<!-- .IN "libX11" -->
<!-- .IN "linking applications" -->
<!-- .IN "compiling applications" -->
    </para>
  </listitem>
  <listitem>
    <para>
<literallayout class="monospaced">
cc -o <emphasis remap='I'>application</emphasis> <emphasis remap='I'>application</emphasis>.c \-lXaw \-lXmu \-lXt \
\-lSM \-lICE \-lXext \-lX11
</literallayout>
    </para>
  </listitem>
</orderedlist>
</sect3>
<sect3 id="Changing_Resource_Values">
<title>Changing Resource Values</title>
<!-- .IN "resource" "" -->
<para>
<!-- .LP -->
The Intrinsics support two methods of changing the default resource
values; the resource manager, and an argument list passed into
XtCreateWidget.  While resources values will get updated no matter
which method you use, the two methods provide slightly different
functionality.
<variablelist>
  <varlistentry>
    <term>Resource Manager</term>
    <listitem>
      <para>
This method picks up resource definitions described in <emphasis remap='I'>Xlib - C Language Interface</emphasis> from
many different locations at run time.  The locations most important to
the application programmer are the <emphasis remap='I'>fallback resources</emphasis> and the
<emphasis remap='I'>app-defaults</emphasis> file, (see <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis> for the complete list).
Since these resource are loaded at run time, they can be overridden by
the user, allowing an application to be customized to fit the
particular needs of each individual user.  These values can also be
modified without the need to rebuild the application, allowing rapid
prototyping of user interfaces.  Application programmers should use
resources in preference to hard-coded values whenever possible.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>Argument Lists</term>
    <listitem>
      <para>
The values passed into the widget at creation time via an argument list
cannot be modified by the user, and allow no opportunity for
customization.  It is used to set resources that cannot be specified as
strings (e.g. callback lists) or resources that should not be
overridden (e.g. window depth) by the user.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<sect4 id="Specifying_Resources">
<title>Specifying Resources</title>
<para>
<!-- .LP -->
It is important for all X Toolkit application programmers to
understand how to use the X Resource Manager to specify resources for
widgets in an X application.  This section will describe the most common
methods used to specify these resources, and how to use the X Resource
manager.
<!-- .IN "xrdb" -->
<variablelist>
  <varlistentry>
    <term>
      <function>Xrdb</function>
    </term>
    <listitem>
      <para>
The <function>xrdb</function> utility may be used to load a file containing
resources into the X server.   Once the resources are loaded, the
resources will affect any new applications started on the display that
they were loaded onto.
<!-- .IN "application defaults" -->
<!-- .IN "app-defaults" -->
<!-- .IN "/usr/lib/X11/app-defaults" -->
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>Application Defaults</term>
    <listitem>
      <para>
The application defaults (app-defaults) file (normally in
/usr/lib/X11/app-defaults/<emphasis remap='I'>classname</emphasis>) for an application is loaded
whenever the application is started.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
The resource specification has two colon-separated parts, a name, and
a value.  The <emphasis remap='I'>value</emphasis> is a string whose format is dependent on the
resource specified by <emphasis remap='I'>name</emphasis>.  <emphasis remap='I'>Name</emphasis> is constructed by
appending a resource name to a full widget name.
</para>
<para>
<!-- .LP -->
The full widget name is a list of the name of every ancestor of the
desired widget separated by periods (.).  Each widget also has a class
associated with it.  A class is a type of widget (e.g. Label or
Scrollbar or Box).  Notice that class names, by convention, begin with
capital letters and instance names begin with lower case letters.  The
class of any widget may be used in place of its name in a resource
specification.  Here are a few examples:
<variablelist>
  <varlistentry>
    <term>
      xman.form.button1
    </term>
    <listitem>
      <para>
This is a fully specified resource name, and will affect only widgets
called button1 that are children of widgets called form that are
children of
applications named xman.  (Note that while typically two widgets that
are siblings will have different names, it is not prohibited.)

      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      Xman.Form.Command
    </term>
    <listitem>
      <para>
This will match any Command widget that is a child of a Form widget
that is itself a child of an application of class <emphasis remap='I'>Xman</emphasis>.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      Xman.Form.button1
    </term>
    <listitem>
      <para>
This is a mixed resource name with both widget names and classes specified.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
This syntax allows an application programmer to specify any widget
in the widget tree.  To match more than one widget (for example a user
may want to make all Command buttons blue), use an asterisk (*)
instead of a period.  When an asterisk is used, any number of widgets
(including zero) may exist between the two widget names. For example:
<variablelist>
  <varlistentry>
    <term>
      Xman*Command
    </term>
    <listitem>
      <para>
This matches all Command widgets in the Xman application.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      Foo*button1
    </term>
    <listitem>
      <para>
This matches any widget in the Foo application that is named <emphasis remap='I'>button1</emphasis>.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
The root of all application widget trees is the widget returned by
<xref linkend='XtAppInitialize' xrefstyle='select: title'/>.  Even though this is actually an
ApplicationShell widget, the toolkit replaces its widget class with the
class name of the application.  The name of this widget is either
the name used to invoke the application (<function>argv[0]</function>) or the name of
the application specified using the standard <emphasis remap='I'>-name</emphasis> command line
option supported by the Intrinsics.
</para>
<para>
<!-- .LP -->
The last step in constructing the resource name is to append the name of
the resource with either a period or asterisk to the full or partial
widget name already constructed.
<variablelist>
  <varlistentry>
    <term>
      *foreground:Blue
    </term>
    <listitem>
      <para>
Specifies that all widgets in all applications will have a foreground
color of blue.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      Xman*borderWidth:10
    </term>
    <listitem>
      <para>
Specifies that all widgets in an application whose class is Xman will
have a border width of 10 (pixels).
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      xman.form.button1.label:Testing
    </term>
    <listitem>
      <para>
Specifies that a particular widget in the xman application will have a
label named <emphasis remap='I'>Testing</emphasis>.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
An exclamation point (!) in the first column of a line indicates
that the rest of the line should be treated as a comment.
</para>
<para>
<!-- .LP -->
<function>Final Words</function>
</para>
<para>
<!-- .LP -->
The Resource manager is a powerful tool that can be used very
effectively to customize X Toolkit applications at run time by either the
application programmer or the user.  Some final points to note:
</para>
<itemizedlist>
  <listitem>
    <para>
An application programmer may add new resources to their
application.  These resources are associated with the global
application, and not any particular widget.  The X Toolkit function used for
adding the application resources is <function>XtGetApplicationResources</function>.
<!-- .IN "XtGetApplicationResources" -->
    </para>
  </listitem>
  <listitem>
    <para>
Be careful when creating resource files.  Since widgets will
ignore resources that they do not understand, any spelling
errors will cause a resource to have no effect.
    </para>
  </listitem>
  <listitem>
    <para>
Only one resource line will match any given resource.  There is a set
of precedence rules, which take the following general stance.
<!-- .ta 10n -->
    </para>
  </listitem>
  <listitem>
    <itemizedlist>
      <listitem>
        <para>
More specific overrides less specific, thus period always overrides asterisk.
        </para>
      </listitem>
      <listitem>
        <para>
Names on the left are more specific and override names on the right.
        </para>
      </listitem>
      <listitem>
        <para>
When resource specifications are exactly the same, user defaults
will override program defaults.
        </para>
      </listitem>
    </itemizedlist>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
For a complete explanation of the rules of precedence, and
other specific topics see <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis> and <emphasis remap='I'>Xlib - C Language Interface</emphasis>.
</para>
</sect4>
<sect4 id="Creating_Argument_Lists">
<title>Creating Argument Lists</title>
<!-- .IN "argument lists" "" "@DEF@" -->
<para>
<!-- .LP -->
To set up an argument list for the inline specification of widget attributes,
you may use any of the four approaches discussed in this section.
Each resource name has a global symbol associated with it.  This
global symbol has the form XtN<emphasis remap='I'>resource name</emphasis>.  For example, the
symbol for ``foreground'' is <function>XtNforeground</function>. For further information,
see the <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>.
</para>
<para>
<!-- .LP -->
Argument are specified by using the following structure:
<!-- .IN "ArgList" "" "@DEF@" -->
<!-- .IN "Arg" "" "@DEF@" -->
</para>
<para>
<!-- .LP -->
<literallayout class="monospaced">
<!-- .TA .5i 1.5i -->
<!-- .ta .5i 1.5i -->
typedef struct {
	String name;
	XtArgVal value;
} Arg, *ArgList;
</literallayout>
</para>
<para>
<!-- .LP -->
The first approach is to statically initialize the argument list.
For example:
</para>
<para>
<!-- .LP -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
static Arg arglist[] = {
	{XtNwidth, (XtArgVal) 400},
	{XtNheight, (XtArgVal) 300},
};
</literallayout>
</para>
<para>
<!-- .LP -->
This approach is convenient for lists that do not need to be computed
at runtime and makes adding or deleting new elements easy.
The
<!-- .IN "XtNumber" -->
<function>XtNumber</function>
macro is used to compute the number of elements in the argument list,
preventing simple programming errors:
</para>
<para>
<!-- .LP -->
<literallayout class="monospaced">
XtCreateWidget(<emphasis remap='I'>name</emphasis>, <emphasis remap='I'>class</emphasis>, <emphasis remap='I'>parent</emphasis>, <emphasis remap='I'>arglist</emphasis>, XtNumber(<emphasis remap='I'>arglist</emphasis>));
</literallayout>
<!-- .IN "XtSetArg" "" "@DEF@" -->
</para>
<para>
<!-- .LP -->
The second approach is to use the
<function>XtSetArg</function>
macro.
For example:
</para>
<para>
<!-- .LP -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
Arg arglist[10];
XtSetArg(arglist[1], XtNwidth, 400);
XtSetArg(arglist[2], XtNheight, 300);
</literallayout>
</para>
<para>
<!-- .LP -->
To make it easier to insert and delete entries,
you also can use a variable index:
</para>
<para>
<!-- .LP -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
Arg arglist[10];
Cardinal i=0;
XtSetArg(arglist[i], XtNwidth,  400);       i++;
XtSetArg(arglist[i], XtNheight, 300);       i++;
</literallayout>
</para>
<para>
<!-- .LP -->
The i variable can then be used as the argument list count in the widget
create function.
In this example,
<!-- .IN "XtNumber" -->
<function>XtNumber</function>
would return 10, not 2, and therefore is not useful.
<!-- .NT -->
You should not use auto-increment or auto-decrement
within the first argument to
<function>XtSetArg .</function>
As it is currently implemented,
<function>XtSetArg</function>
is a macro that dereferences the first argument twice.
<!-- .NE -->
</para>
<para>
<!-- .LP -->
The third approach is to individually set the elements of the
argument list array:
</para>
<para>
<!-- .LP -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
Arg arglist[10];
arglist[0].name  = XtNwidth;
arglist[0].value = (XtArgVal) 400;
arglist[1].name  = XtNheight;
arglist[1].value = (XtArgVal) 300;
</literallayout>
</para>
<para>
<!-- .LP -->
Note that in this example, as in the previous example,
<!-- .IN "XtNumber" -->
<function>XtNumber</function>
would return 10, not 2, and therefore would not be useful.
</para>
<para>
<!-- .LP -->
The fourth approach is to use a mixture of the first and third approaches:
you can statically define the argument list but modify some entries at runtime.
For example:
</para>
<para>
<!-- .LP -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
static Arg arglist[] = {
	{XtNwidth, (XtArgVal) 400},
	{XtNheight, (XtArgVal) NULL},
};
arglist[1].value = (XtArgVal) 300;
</literallayout>
</para>
<para>
<!-- .LP -->
In this example,
<!-- .IN "XtNumber" -->
<function>XtNumber</function>
can be used, as in the first approach, for easier code maintenance.
</para>
</sect4>
</sect3>
</sect2>
<sect2 id="Example_Programs">
<title>Example Programs</title>
<!-- .XS -->
<!-- 	Example Programs -->
<!-- .XE -->
<!-- .IN "examples" -->
<para>
<!-- .LP -->
The best way to understand how to use any programming library is by
trying some simple examples.  A collection of example programs that
introduces each of the widgets in that Athena widget set, as well as many
important toolkit programming concepts, is available in the X11R5 contrib
release as distributed by the X Consortium.  It can be found in the
directory <filename>contrib/examples/Xaw</filename> in the archive
at <ulink url="http://www.x.org/releases/X11R5/contrib-1.tar.Z" />
See the <filename>README</filename> file from that directory for a guide
to the examples.
</para>
</sect2>
</sect1>
</chapter>