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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<title>Migration Checklist: GTK+ 2 Reference Manual</title>
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<div class="chapter">
<div class="titlepage"><div><div><h2 class="title">
<a name="gtk-migrating-checklist"></a>Migration Checklist</h2></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="gtk-migrating-checklist.html#checklist-popup-menu">Implement GtkWidget::popup_menu</a></span></dt>
<dt><span class="section"><a href="checklist-gdkeventexpose-region.html">Use GdkEventExpose.region</a></span></dt>
<dt><span class="section"><a href="checklist-modifiers.html">Test for modifier keys correctly</a></span></dt>
<dt><span class="section"><a href="checklist-named-icons.html">Use named icons</a></span></dt>
</dl></div>
<p>
This chapter includes a checklist of things you need to do to
ensure that your programs are good citizens in the GTK+ world. By
paying attention to the points in the checklist, you ensure that
many automatic features of GTK+ will work correctly in your
program.
</p>
<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="checklist-popup-menu"></a>Implement GtkWidget::popup_menu</h2></div></div></div>
<p><b>Why. </b>
By handling this signal, you let widgets have
context-sensitive menus that can be invoked with the standard
key bindings.
</p>
<p>
The <a class="link" href="GtkWidget.html#GtkWidget-popup-menu" title="The “popup-menu” signal"><span class="type">“popup-menu”</span></a> signal instructs the widget for which
it is emitted to create a context-sensitive popup menu. By default,
the key binding mechanism is set to
emit this signal when the
<span class="keycap"><strong>Shift</strong></span>+<span class="keycap"><strong>F10</strong></span>
or <span class="keycap"><strong>Menu</strong></span> keys are pressed while a widget has the
focus. If a widget in your application shows a popup menu when
you press a mouse button, you can make it work as well through
the normal key binding mechanism in the following fahion:
</p>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
<p>
Write a function to create and show a popup menu. This
function needs to know the button number and the event's
time to pass them to <a class="link" href="GtkMenu.html#gtk-menu-popup" title="gtk_menu_popup ()"><code class="function">gtk_menu_popup()</code></a>. You can implement
such a function like this:
</p>
<a name="do_popup_menu"></a><pre class="programlisting">
static void
do_popup_menu (GtkWidget *my_widget, GdkEventButton *event)
{
GtkWidget *menu;
int button, event_time;
menu = gtk_menu_new ();
g_signal_connect (menu, "deactivate",
G_CALLBACK (gtk_widget_destroy), NULL);
/* ... add menu items ... */
if (event)
{
button = event->button;
event_time = event->time;
}
else
{
button = 0;
event_time = gtk_get_current_event_time ();
}
gtk_menu_attach_to_widget (GTK_MENU (menu), my_widget, NULL);
gtk_menu_popup (GTK_MENU (menu), NULL, NULL, NULL, NULL,
button, event_time);
}
</pre>
</li>
<li class="listitem">
<p>
In your <a class="link" href="GtkWidget.html#GtkWidget-button-press-event" title="The “button-press-event” signal"><span class="type">“button-press-event”</span></a> handler, call this function
when you need to pop up a menu:
</p>
<pre class="programlisting">
static gboolean
my_widget_button_press_event_handler (GtkWidget *widget, GdkEventButton *event)
{
/* Ignore double-clicks and triple-clicks */
if (event->button == 3 && event->type == GDK_BUTTON_PRESS)
{
do_popup_menu (widget, event);
return TRUE;
}
return FALSE;
}
</pre>
</li>
<li class="listitem">
<p>
Implement a handler for the <a class="link" href="GtkWidget.html#GtkWidget-popup-menu" title="The “popup-menu” signal"><span class="type">“popup-menu”</span></a> signal:
</p>
<pre class="programlisting">
static gboolean
my_widget_popup_menu_handler (GtkWidget *widget)
{
do_popup_menu (widget, NULL);
return TRUE;
}
</pre>
</li>
</ol></div>
<div class="note"><p>
If you do not pass a positioning function to <a class="link" href="GtkMenu.html#gtk-menu-popup" title="gtk_menu_popup ()"><code class="function">gtk_menu_popup()</code></a>,
it will show the menu at the mouse position by default. This
is what you usually want when the menu is shown as a result of
pressing a mouse button. However, if you press the
<span class="keycap"><strong>Shift</strong></span>+<span class="keycap"><strong>F10</strong></span>
or <span class="keycap"><strong>Menu</strong></span> keys while the widget is focused, the
mouse cursor may not be near the widget at all. In the <a class="link" href="gtk-migrating-checklist.html#do_popup_menu">example above</a>, you may want to
provide your own <a class="link" href="GtkMenu.html#GtkMenuPositionFunc" title="GtkMenuPositionFunc ()">menu-positioning function</a>
in the case where the <em class="parameter"><code>event</code></em> is
<code class="literal">NULL</code>. This function should compute the desired position for
a menu when it is invoked through the keyboard. For example,
<a class="link" href="GtkEntry.html" title="GtkEntry"><span class="type">GtkEntry</span></a> aligns the top edge of its popup menu with the bottom
edge of the entry.
</p></div>
<div class="note"><p>
For the standard key bindings to work, your widget must be
able to take the keyboard focus. In general, widgets should
be fully usable through the keyboard and not just the mouse.
The very first step of this is to ensure that your widget
turns on the <a class="link" href="GtkWidget.html#GTK-CAN-FOCUS:CAPS"><code class="literal">GTK_CAN_FOCUS</code></a> flag.
</p></div>
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