path: root/specs/CH05.xml

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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd">

<chapter id='Pop_Up_Widgets'>
<title>Pop-Up Widgets</title>
<para>
Pop-up widgets are used to create windows outside of the
window hierarchy defined by the widget tree.
Each pop-up child has a window that is a descendant of the root window,
so that the pop-up window is not clipped by the pop-up widget's parent window.
Therefore, pop-ups are created and attached differently to their widget parent
than normal widget children.
</para>

<para>
A parent of a pop-up widget does not actively manage its pop-up children;
in fact, it usually does not operate upon them in any way.
The <emphasis remap='I'>popup_list</emphasis> field in the
<function>CorePart</function>
structure contains the list of its pop-up children.
This pop-up list exists mainly to provide the proper place in the widget
hierarchy for the pop-up to get resources and to provide a place for
<xref linkend='XtDestroyWidget' xrefstyle='select: title'/>
to look for all extant children.
</para>

<para>
A
composite
widget can have both normal and pop-up children.
A pop-up can be popped up from almost anywhere, not just by its parent.
The term <emphasis remap='I'>child</emphasis> always refers to a normal, geometry-managed widget
on the composite widget's list of children, and the term
<emphasis remap='I'>pop-up child</emphasis> always refers to a
widget on the pop-up list.
</para>

<sect1 id="Pop_Up_Widget_Types">
<title>Pop-Up Widget Types</title>
<para>
There are three kinds of pop-up widgets:
</para>

<itemizedlist spacing='compact'>
  <listitem>
    <para>
Modeless pop-ups
    </para>
    <para>
A modeless pop-up (for example, a dialog box that does not prevent
continued interaction with the rest of the application)
can usually be manipulated by the window manager
and looks like any other application window from the
user's point of view.
The application main window itself is a special case of a modeless pop-up.
    </para>
  </listitem>
  <listitem>
    <para>
Modal pop-ups
    </para>
    <para>
A modal pop-up (for example, a dialog box that requires user input to
continue)
can sometimes be manipulated by the window manager,
and except for events that occur in the dialog box,
it disables user-event distribution to the rest of the application.
    </para>
  </listitem>
  <listitem>
    <para>
Spring-loaded pop-ups
    </para>
    <para>
A spring-loaded pop-up (for example, a menu)
can seldom be manipulated by the window manager,
and except for events that occur in the pop-up or its descendants,
it disables user-event distribution to all other applications.
    </para>
  </listitem>
</itemizedlist>
<para>
Modal pop-ups and spring-loaded pop-ups are very similar and should be coded as
if they were the same.
In fact, the same widget (for example, a ButtonBox or Menu widget) can be used both
as a modal pop-up and as a spring-loaded pop-up within the same application.
The main difference is that spring-loaded pop-ups are brought up
with the pointer and, because of the grab that the pointer button causes,
require different processing by the Intrinsics.
Furthermore, all user input remap events occurring outside the spring-loaded
pop-up (e.g., in a descendant) are also delivered to the spring-loaded
pop-up after they have been dispatched to the appropriate descendant, so
that, for example, button-up can take down a spring-loaded pop-up no
matter where the
button-up occurs.
</para>

<para>
Any kind of pop-up, in turn, can pop up other widgets.
Modal and spring-loaded pop-ups can constrain user events to
the most recent such pop-up or allow user events to be dispatched
to any of the modal or spring-loaded pop-ups
currently mapped.
</para>

<para>
Regardless of their type,
all pop-up widget classes are responsible for communicating with the
X window manager and therefore are subclasses of
one of the
Shell
widget classes.
</para>
</sect1>

<sect1 id="Creating_a_Pop_Up_Shell">
<title>Creating a Pop-Up Shell</title>
<para>
For a widget to be popped up,
it must be the child of a pop-up shell widget.
None of the Intrinsics-supplied shells will
simultaneously manage more than one child.
Both the shell and child taken together are referred to as the pop-up.
When you need to use a pop-up,
you always refer to the pop-up by the pop-up shell,
not the child.
</para>

<para>
To create a pop-up shell, use
<xref linkend='XtCreatePopupShell' xrefstyle='select: title'/>.
</para>

<funcsynopsis id='XtCreatePopupShell'>
<funcprototype>
<funcdef>Widget <function>XtCreatePopupShell</function></funcdef>
   <paramdef>const char * <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>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>name</emphasis>
    </term>
    <listitem>
      <para>
Specifies the instance name for the created shell widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>widget_class</emphasis>
    </term>
    <listitem>
      <para>
Specifies the widget class pointer for the created shell widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>parent</emphasis>
    </term>
    <listitem>
      <para>
Specifies the parent widget.  Must be of class Core or any subclass thereof.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>args</emphasis>
    </term>
    <listitem>
      <para>
Specifies the argument list to override any other resource specifications.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>num_args</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of entries in the argument list.
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
The
<xref linkend='XtCreatePopupShell' xrefstyle='select: title'/>
function ensures that the specified class is a subclass of
Shell
and, rather than using insert_child to attach the widget to the parent's
<emphasis remap='I'>children</emphasis> list,
attaches the shell to the parent's <emphasis remap='I'>popup_list</emphasis> directly.
</para>

<para>
The screen resource for this widget is determined by first scanning
<emphasis remap='I'>args</emphasis> for the XtNscreen argument.  If no XtNscreen argument is
found, the resource database associated with the parent's screen
is queried for the resource <emphasis remap='I'>name</emphasis>.screen, class
<emphasis remap='I'>Class</emphasis>.Screen where <emphasis remap='I'>Class</emphasis> is the <emphasis remap='I'>class_name</emphasis>
field from the
<function>CoreClassPart</function>
of the specified <emphasis remap='I'>widget_class</emphasis>.
If this query fails, the parent's screen is used.
Once the screen is determined,
the resource database associated with that screen is used to retrieve
all remaining resources for the widget not specified in
<emphasis remap='I'>args</emphasis>.
</para>

<para>
A spring-loaded pop-up invoked from a translation table via
<xref linkend='XtMenuPopup' xrefstyle='select: title'/>
must already exist
at the time that the translation is invoked,
so the translation manager can find the shell by name.
Pop-ups invoked in other ways can be created when
the pop-up actually is needed.
This delayed creation of the shell is particularly useful when you pop up
an unspecified number of pop-ups.
You can look to see if an appropriate unused shell (that is, not
currently popped up) exists and create a new shell if needed.
</para>

<para>
To create a pop-up shell using varargs lists, use
<xref linkend='XtVaCreatePopupShell' xrefstyle='select: title'/>.
</para>

<funcsynopsis id='XtVaCreatePopupShell'>
<funcprototype>
<funcdef>Widget <function>XtVaCreatePopupShell</function></funcdef>
   <paramdef>const char * <parameter>name</parameter></paramdef>
   <paramdef>WidgetClass <parameter>widget_class</parameter></paramdef>
   <paramdef>Widget <parameter>parent</parameter></paramdef>
   <paramdef><parameter>...</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>name</emphasis>
    </term>
    <listitem>
      <para>
Specifies the instance name for the created shell widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>widget_class</emphasis>
    </term>
    <listitem>
      <para>
Specifies the widget class pointer for the created shell widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>parent</emphasis>
    </term>
    <listitem>
      <para>
Specifies the parent widget.  Must be of class Core or any subclass thereof.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>...</term>
    <listitem>
      <para>
Specifies the variable argument list to override any other
resource specifications.
    </para>
  </listitem>
  </varlistentry>
</variablelist>


<para>
<xref linkend='XtVaCreatePopupShell' xrefstyle='select: title'/>
is identical in function to
<xref linkend='XtCreatePopupShell' xrefstyle='select: title'/>
with <emphasis remap='I'>the</emphasis> args and <emphasis remap='I'>num_args</emphasis> parameters replaced by a varargs list as
described in Section 2.5.1.
</para>
</sect1>

<sect1 id="Creating_Pop_Up_Children">
<title>Creating Pop-Up Children</title>
<para>
Once a pop-up shell is created,
the single child of the pop-up shell can be created
either statically or dynamically.
</para>

<para>
At startup,
an application can create the child of the pop-up shell,
which is appropriate for pop-up children composed of a fixed set
of widgets.
The application can change the state of the subparts of
the pop-up child as the application state changes.
For example, if an application creates a static menu,
it can call
<xref linkend='XtSetSensitive' xrefstyle='select: title'/>
(or, in general,
<xref linkend='XtSetValues' xrefstyle='select: title'/>)
on any of the buttons that make up the menu.
Creating the pop-up child early means that pop-up time is minimized,
especially if the application calls
<xref linkend='XtRealizeWidget' xrefstyle='select: title'/>
on the pop-up shell at startup.
When the menu is needed,
all the widgets that make up the menu already exist and need only be mapped.
The menu should pop up as quickly as the X server can respond.
</para>

<para>
Alternatively,
an application can postpone the creation of the child until it is needed,
which minimizes application startup time and allows the pop-up child to
reconfigure itself each time it is popped up.
In this case,
the pop-up child creation routine might poll the application
to find out if it should change the sensitivity of any of its subparts.
</para>

<para>
Pop-up child creation does not map the pop-up,
even if you create the child and call
<xref linkend='XtRealizeWidget' xrefstyle='select: title'/>
on the pop-up shell.
</para>

<para>
All shells have pop-up and pop-down callbacks,
which provide the opportunity either to make last-minute changes to a
pop-up child before it is popped up or to change it after it is popped down.
Note that excessive use of pop-up callbacks can make
popping up occur more slowly.
</para>
</sect1>

<sect1 id="Mapping_a_Pop_Up_Widget">
<title>Mapping a Pop-Up Widget</title>
<para>
Pop-ups can be popped up through several mechanisms:
</para>
<itemizedlist spacing='compact'>
  <listitem>
    <para>
A call to
<xref linkend='XtPopup' xrefstyle='select: title'/>
or
<xref linkend='XtPopupSpringLoaded' xrefstyle='select: title'/>.
    </para>
  </listitem>
  <listitem>
    <para>
One of the supplied callback procedures
<xref linkend='XtCallbackNone' xrefstyle='select: title'/>,
<xref linkend='XtCallbackNonexclusive' xrefstyle='select: title'/>,
or
<xref linkend='XtCallbackExclusive' xrefstyle='select: title'/>.
    </para>
  </listitem>
  <listitem>
    <para>
The standard translation action
<xref linkend='XtMenuPopup' xrefstyle='select: title'/>.
    </para>
  </listitem>
</itemizedlist>

<para>
Some of these routines take an argument of type
<function>XtGrabKind</function>,
which is defined as
</para>
<programlisting>
typedef enum {XtGrabNone, XtGrabNonexclusive, XtGrabExclusive} XtGrabKind;
</programlisting>

<para>
The create_popup_child_proc procedure pointer
in the shell widget instance record is of type
<xref linkend='XtCreatePopupChildProc' xrefstyle='select: title'/>.
</para>

<funcsynopsis id='XtCreatePopupChildProc'>
<funcprototype>
<funcdef>typedef void *<function>XtCreatePopupChildProc</function></funcdef>
   <paramdef>Widget <parameter>w</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the shell widget being popped up.
    </para>
  </listitem>
  </varlistentry>
</variablelist>


<para>
To map a pop-up from within an application, use
<xref linkend='XtPopup' xrefstyle='select: title'/>.
</para>

<funcsynopsis id='XtPopup'>
<funcprototype>
<funcdef>void <function>XtPopup</function></funcdef>
   <paramdef>Widget <parameter>popup_shell</parameter></paramdef>
   <paramdef>XtGrabKind <parameter>grab_kind</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>popup_shell</emphasis>
    </term>
    <listitem>
      <para>
Specifies the shell widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>grab_kind</emphasis>
    </term>
    <listitem>
      <para>
Specifies the way in which user events should be constrained.
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
The
<xref linkend='XtPopup' xrefstyle='select: title'/>
function performs the following:
</para>
<itemizedlist spacing='compact'>
  <listitem>
    <para>
Calls
<xref linkend='XtCheckSubclass' xrefstyle='select: title'/>
to ensure <emphasis remap='I'>popup_shell</emphasis>'s class is a subclass of
<function>shellWidgetClass</function>.
    </para>
  </listitem>
  <listitem>
    <para>
Raises the window and returns if the shell's <emphasis remap='I'>popped_up</emphasis> field is already
<function>True</function>.
    </para>
  </listitem>
  <listitem>
    <para>
Calls the callback procedures on the shell's <emphasis remap='I'>popup_callback</emphasis> list,
specifying a pointer to the value of <emphasis remap='I'>grab_kind</emphasis> as the <emphasis remap='I'>call_data</emphasis>
argument.
    </para>
  </listitem>
  <listitem>
    <para>
Sets the shell <emphasis remap='I'>popped_up</emphasis> field to
<function>True</function>,
the shell <emphasis remap='I'>spring_loaded</emphasis> field to
<function>False</function>,
and the shell <emphasis remap='I'>grab_kind</emphasis> field from <emphasis remap='I'>grab_kind</emphasis>.
    </para>
  </listitem>
  <listitem>
    <para>
If the shell's <emphasis remap='I'>create_popup_child_proc</emphasis> field is non-NULL,
<xref linkend='XtPopup' xrefstyle='select: title'/>
calls it with <emphasis remap='I'>popup_shell</emphasis> as the parameter.
    </para>
  </listitem>
  <listitem>
    <para>
If <emphasis remap='I'>grab_kind</emphasis> is either
<function>XtGrabNonexclusive</function>
or
<function>XtGrabExclusive</function>,
it calls
    </para>
<programlisting>
XtAddGrab(<emphasis remap='I'>popup_shell</emphasis>, (<emphasis remap='I'>grab_kind</emphasis> == XtGrabExclusive), False)
</programlisting>
  </listitem>
  <listitem>
    <para>
Calls
<xref linkend='XtRealizeWidget' xrefstyle='select: title'/>
with <emphasis remap='I'>popup_shell</emphasis> specified.
    </para>
  </listitem>
  <listitem>
    <para>
Calls
<function>XMapRaised</function>
with the window of <emphasis remap='I'>popup_shell</emphasis>.
    </para>
  </listitem>
</itemizedlist>
<para>
To map a spring-loaded pop-up from within an application, use
<xref linkend='XtPopupSpringLoaded' xrefstyle='select: title'/>.
</para>

<funcsynopsis id='XtPopupSpringLoaded'>
<funcprototype>
<funcdef>void <function>XtPopupSpringLoaded</function></funcdef>
   <paramdef>Widget <parameter>popup_shell</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>popup_shell</emphasis>
    </term>
    <listitem>
      <para>
Specifies the shell widget to be popped up.
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
The
<xref linkend='XtPopupSpringLoaded' xrefstyle='select: title'/>
function performs exactly as
<xref linkend='XtPopup' xrefstyle='select: title'/>
except that it sets the shell <emphasis remap='I'>spring_loaded</emphasis> field to
<function>True</function>
and always calls
<xref linkend='XtAddGrab' xrefstyle='select: title'/>
with <emphasis remap='I'>exclusive</emphasis>
<function>True</function>
and <emphasis remap='I'>spring-loaded</emphasis>
<function>True</function>.
</para>

<para>
To map a pop-up from a given widget's callback list,
you also can register one of the
<xref linkend='XtCallbackNone' xrefstyle='select: title'/>,
<xref linkend='XtCallbackNonexclusive' xrefstyle='select: title'/>,
or
<xref linkend='XtCallbackExclusive' xrefstyle='select: title'/>
convenience routines as callbacks, using the pop-up shell widget as the
client data.
</para>

<funcsynopsis id='XtCallbackNone'>
<funcprototype>
<funcdef>void <function>XtCallbackNone</function></funcdef>
   <paramdef>Widget <parameter>w</parameter></paramdef>
   <paramdef>XtPointer <parameter>client_data</parameter></paramdef>
   <paramdef>XtPointer <parameter>call_data</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>client_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the pop-up shell.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>call_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the callback data argument,
which is not used by this procedure.
    </para>
  </listitem>
  </varlistentry>
</variablelist>


<funcsynopsis id='XtCallbackNonexclusive'>
<funcprototype>
<funcdef>void <function>XtCallbackNonexclusive</function></funcdef>
   <paramdef>Widget <parameter>w</parameter></paramdef>
   <paramdef>XtPointer <parameter>client_data</parameter></paramdef>
   <paramdef>XtPointer <parameter>call_data</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>client_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the pop-up shell.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>call_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the callback data argument,
which is not used by this procedure.
    </para>
  </listitem>
  </varlistentry>
</variablelist>


<funcsynopsis id='XtCallbackExclusive'>
<funcprototype>
<funcdef>void <function>XtCallbackExclusive</function></funcdef>
   <paramdef>Widget <parameter>w</parameter></paramdef>
   <paramdef>XtPointer <parameter>client_data</parameter></paramdef>
   <paramdef>XtPointer <parameter>call_data</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>client_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the pop-up shell.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>call_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the callback data argument,
which is not used by this procedure.
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
The
<xref linkend='XtCallbackNone' xrefstyle='select: title'/>,
<xref linkend='XtCallbackNonexclusive' xrefstyle='select: title'/>,
and
<xref linkend='XtCallbackExclusive' xrefstyle='select: title'/>
functions call
<xref linkend='XtPopup' xrefstyle='select: title'/>
with the shell specified by the <emphasis remap='I'>client_data</emphasis> argument
and <emphasis remap='I'>grab_kind</emphasis> set as the name specifies.
<xref linkend='XtCallbackNone' xrefstyle='select: title'/>,
<xref linkend='XtCallbackNonexclusive' xrefstyle='select: title'/>,
and
<xref linkend='XtCallbackExclusive' xrefstyle='select: title'/>
specify
<function>XtGrabNone</function>,
<function>XtGrabNonexclusive</function>,
and
<function>XtGrabExclusive</function>,
respectively.
Each function then sets the widget that executed the callback list
to be insensitive by calling
<xref linkend='XtSetSensitive' xrefstyle='select: title'/>.
Using these functions in callbacks is not required.
In particular,
an application must provide customized code for
callbacks that create pop-up shells dynamically or that must do more than
desensitizing the button.
</para>

<para>
Within a translation table,
to pop up a menu when a key or pointer button is pressed or when the pointer
is moved into a widget, use
<xref linkend='XtMenuPopup' xrefstyle='select: title'/>,
or its synonym,
<function>MenuPopup</function>.
From a translation writer's point of view,
the definition for this translation action is
</para>

<funcsynopsis id='XtMenuPopup'>
<funcprototype>
<funcdef>void <function>XtMenuPopup</function></funcdef>
   <paramdef>String <parameter>shell_name</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>shell_name</emphasis>
    </term>
    <listitem>
      <para>
Specifies the name of the shell widget to pop up.
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
<xref linkend='XtMenuPopup' xrefstyle='select: title'/>
is known to the translation manager,
which registers the corresponding built-in action procedure
<function>XtMenuPopupAction</function>
using
<xref linkend='XtRegisterGrabAction' xrefstyle='select: title'/>
specifying <emphasis remap='I'>owner_events</emphasis>
<function>True</function>,
<emphasis remap='I'>event_mask</emphasis>
<function>ButtonPressMask</function>
<function>|</function>
<function>ButtonReleaseMask</function>,
and <emphasis remap='I'>pointer_mode</emphasis> and <emphasis remap='I'>keyboard_mode</emphasis>
<function>GrabModeAsync</function>.
</para>

<para>
If
<xref linkend='XtMenuPopup' xrefstyle='select: title'/>
is invoked on
<function>ButtonPress</function>,
it calls
<xref linkend='XtPopupSpringLoaded' xrefstyle='select: title'/>
on the specified shell widget.
If
<xref linkend='XtMenuPopup' xrefstyle='select: title'/>
is invoked on
<function>KeyPress</function>
or
<function>EnterWindow</function>,
it calls
<xref linkend='XtPopup' xrefstyle='select: title'/>
on the specified shell widget with <emphasis remap='I'>grab_kind</emphasis> set to
<function>XtGrabNonexclusive</function>.
Otherwise, the translation manager generates a
warning message and ignores the action.
</para>

<para>
<xref linkend='XtMenuPopup' xrefstyle='select: title'/>
tries to find the shell by searching the widget tree starting at
the widget in which it is invoked.
If it finds a shell with the specified name in the pop-up children of
that widget, it pops up the shell with the appropriate parameters.
Otherwise, it moves up the parent chain to find a pop-up child with the
specified name.
If
<xref linkend='XtMenuPopup' xrefstyle='select: title'/>
gets to the application top-level shell widget and has not
found a matching shell, it generates a warning and returns immediately.
</para>
</sect1>

<sect1 id="Unmapping_a_Pop_Up_Widget">
<title>Unmapping a Pop-Up Widget</title>
<para>
Pop-ups can be popped down through several mechanisms:
</para>
<itemizedlist spacing='compact'>
  <listitem>
    <para>
A call to
<xref linkend='XtPopdown' xrefstyle='select: title'/>
    </para>
  </listitem>
  <listitem>
    <para>
The supplied callback procedure
<xref linkend='XtCallbackPopdown' xrefstyle='select: title'/>
    </para>
  </listitem>
  <listitem>
    <para>
The standard translation action
<xref linkend='XtMenuPopdown' xrefstyle='select: title'/>
    </para>
  </listitem>
</itemizedlist>
<para>
To unmap a pop-up from within an application, use
<xref linkend='XtPopdown' xrefstyle='select: title'/>.
</para>

<funcsynopsis id='XtPopdown'>
<funcprototype>
<funcdef>void <function>XtPopdown</function></funcdef>
   <paramdef>Widget <parameter>popup_shell</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>popup_shell</emphasis>
    </term>
    <listitem>
      <para>
Specifies the shell widget to pop down.
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
The
<xref linkend='XtPopdown' xrefstyle='select: title'/>
function performs the following:
</para>
<itemizedlist spacing='compact'>
  <listitem>
    <para>
Calls
<xref linkend='XtCheckSubclass' xrefstyle='select: title'/>
to ensure <emphasis remap='I'>popup_shell</emphasis>'s class is a subclass of
<function>shellWidgetClass</function>.
    </para>
  </listitem>
  <listitem>
    <para>
Checks that the <emphasis remap='I'>popped_up</emphasis> field of <emphasis remap='I'>popup_shell</emphasis> is
<function>True</function>;
otherwise, it returns immediately.
    </para>
  </listitem>
  <listitem>
    <para>
Unmaps <emphasis remap='I'>popup_shell</emphasis>'s window and, if <emphasis remap='I'>override_redirect</emphasis> is
<function>False</function>,
sends a synthetic
<function>UnmapNotify</function>
event as specified by the <emphasis remap='I'>Inter-Client Communication Conventions Manual</emphasis>.
    </para>
  </listitem>
  <listitem>
    <para>
If <emphasis remap='I'>popup_shell</emphasis>'s <emphasis remap='I'>grab_kind</emphasis> is either
<function>XtGrabNonexclusive</function>
or
<function>XtGrabExclusive</function>,
it calls
<xref linkend='XtRemoveGrab' xrefstyle='select: title'/>.
    </para>
  </listitem>
  <listitem>
    <para>
Sets <emphasis remap='I'>popup_shell</emphasis>'s <emphasis remap='I'>popped_up</emphasis> field to
<function>False</function>.
    </para>
  </listitem>
  <listitem>
    <para>
Calls the callback procedures on the shell's <emphasis remap='I'>popdown_callback</emphasis> list,
specifying a pointer to the value of the shell's <emphasis remap='I'>grab_kind</emphasis> field
as the <emphasis remap='I'>call_data</emphasis> argument.
    </para>
  </listitem>
</itemizedlist>
<para>
To pop down a pop-up from a callback list, you may use the callback
<xref linkend='XtCallbackPopdown' xrefstyle='select: title'/>.
</para>

<funcsynopsis id='XtCallbackPopdown'>
<funcprototype>
<funcdef>void <function>XtCallbackPopdown</function></funcdef>
   <paramdef>Widget <parameter>w</parameter></paramdef>
   <paramdef>XtPointer <parameter>client_data</parameter></paramdef>
   <paramdef>XtPointer <parameter>call_data</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>client_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies a pointer to the
<function>XtPopdownID</function>
structure.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>call_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the callback data argument,
which is not used by this procedure.
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
The
<xref linkend='XtCallbackPopdown' xrefstyle='select: title'/>
function casts the <emphasis remap='I'>client_data</emphasis> parameter to a pointer of type
<function>XtPopdownID</function>.
</para>
<programlisting>
typedef struct {
        Widget shell_widget;
        Widget enable_widget;
} XtPopdownIDRec, *XtPopdownID;
</programlisting>
<para>
The <emphasis remap='I'>shell_widget</emphasis> is the pop-up shell to pop down,
and the <emphasis remap='I'>enable_widget</emphasis> is usually the widget that was used to pop it up
in one of the pop-up callback convenience procedures.
</para>

<para>
<xref linkend='XtCallbackPopdown' xrefstyle='select: title'/>
calls
<xref linkend='XtPopdown' xrefstyle='select: title'/>
with the specified <emphasis remap='I'>shell_widget</emphasis>
and then calls
<xref linkend='XtSetSensitive' xrefstyle='select: title'/>
to resensitize <emphasis remap='I'>enable_widget</emphasis>.
</para>

<para>
Within a translation table,
to pop down a spring-loaded menu when a key or pointer button is
released or when the
pointer is moved into a widget, use
<xref linkend='XtMenuPopdown' xrefstyle='select: title'/>
or its synonym,
<function>MenuPopdown</function>.
From a translation writer's point of view,
the definition for this translation action is
</para>

<funcsynopsis id='XtMenuPopdown'>
<funcprototype>
<funcdef>void <function>XtMenuPopdown</function></funcdef>
   <paramdef>String <parameter>shell_name</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>shell_name</emphasis>
    </term>
    <listitem>
      <para>
Specifies the name of the shell widget to pop down.
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
If a shell name is not given,
<xref linkend='XtMenuPopdown' xrefstyle='select: title'/>
calls
<xref linkend='XtPopdown' xrefstyle='select: title'/>
with the widget for which the translation is specified.
If <emphasis remap='I'>shell_name</emphasis> is specified in the translation table,
<xref linkend='XtMenuPopdown' xrefstyle='select: title'/>
tries to find the shell by looking up the widget tree starting at the
widget in which it is invoked.
If it finds a shell with the specified name in the pop-up children
of that widget, it pops down the shell;
otherwise, it moves up the parent chain to find a pop-up child with the
specified name.
If
<xref linkend='XtMenuPopdown' xrefstyle='select: title'/>
gets to the application top-level shell widget
and cannot find a matching shell,
it generates a warning and returns immediately.
</para>
</sect1>
</chapter>