xref: /xsrc/external/mit/libXaw/dist/specs/CH4.xml

<chapter id='Menus'>
<title>Menus</title>
<para>
The Athena widget set provides support for single paned non-hierarchical
popup and pulldown menus.  Since menus are such a common user interface
tool, support for them must be provided in even the most basic widget
sets.  In menuing as in other areas, the Athena Widget Set provides only
basic functionality.
</para>
<para>
Menus in the Athena widget set are implemented as a menu container (the
SimpleMenu widget) and a collection of objects that comprise the
menu entries.  The SimpleMenu widget is itself a direct subclass of the
OverrideShell widget class, so no other shell is necessary when
creating a menu.  The managed children of a SimpleMenu must be
subclasses of the Sme (Simple Menu Entry) object.
</para>
<para>
The Athena widget set provides three classes of Sme objects that may be
used to build menus.
</para>
<para>
<variablelist>
  <varlistentry>
    <term>Sme</term>
    <listitem>
      <para>
The base class of all menu entries.  It may be used as a menu entry
itself to provide blank space in a menu.  "Sme" means "Simple Menu
Entry."
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>SmeBSB</term>
    <listitem>
      <para>
This menu entry provides a selectable entry containing a text string.
A bitmap may also be placed in the left and right margins.  "BSB" means
"Bitmap String Bitmap."
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>SmeLine</term>
    <listitem>
      <para>
This menu entry provides an unselectable entry containing a separator line.
      </para>
    </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
The SimpleMenu widget informs the window manager that it should ignore
its window by setting the <function>Override Redirect</function> flag.  This is the
correct behavior for the press-drag-release style of menu operation.  If
click-move-click or "pinable" menus are desired it is the
responsibility of the application programmer, using the SimpleMenu
resources, to inform the window manager of the menu.
</para>
<para>
To allow easy creation of pulldown menus, a MenuButton widget is
also provided as part of the Athena widget set.
</para>
<sect1 id="Using_the_Menus">
<title>Using the Menus</title>
<!-- .XS -->
<!-- 	Using the Menus -->
<!-- .XE -->
<indexterm><primary>Menus</primary><secondary>using</secondary></indexterm>
<para>
<!-- .LP -->
The default configuration for the menus is press-drag-release.
The menus will typically be
activated by clicking a pointer button while the pointer is over a
MenuButton, causing the menu to appear in a fixed location relative to
that button; this is a <function>pulldown</function> menu.  Menus may also be activated
<indexterm><primary>Menus</primary><secondary>pulldown</secondary></indexterm>
when a specific pointer and/or key sequence is used anywhere in the
application; this is a <function>popup</function> menu (e.g. clicking Ctrl-&lt;pointer
<indexterm><primary>Menus</primary><secondary>popup</secondary></indexterm>
button 1&gt; in the common application <function>xterm</function>).  In this
case the menu should be positioned under
the cursor. Typically menus will be placed so the pointer cursor is on
the first menu entry, or the last entry selected by the user.
</para>
<para>
<!-- .LP -->
The menu remains on the screen as long as the pointer button is held
down.  Moving the pointer will highlight different menu items.
If the pointer leaves the menu, or moves over an entry that cannot
be selected then no menu entry will highlighted.  When the desired menu
entry has been highlighted, releasing the pointer button removes the menu,
and causes any mechanism associated with this entry to be invoked.

</para>
</sect1>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude"  href="SimpleMenu.xml"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude"  href="SmeBSB.xml"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude"  href="SmeLine.xml"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude"  href="Sme.xml"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude"  href="MenuButton.xml"/>
</chapter>