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<H2><A NAME="sec:1.5"><SPAN class="sec-nr">1.5</SPAN> <SPAN class="sec-title">Look-and-feel</SPAN></A></H2>
<P><A NAME="idx:lookandfeel:10"></A><A NAME="idx:Motif:11"></A><A NAME="idx:OpenWindows:12"></A><A NAME="idx:MSWindows:13"></A><font size=-1>XPCE</font>
is not implemented on top of a standard UI library such as Motif,
OpenWindows, or Win32. Instead, it is built on top of its own VWS
defining primitives to create and manipulate windows, draw primitives
such as lines, circles, text and handle user-events.
<P>As a consequence, <font size=-1>XPCE</font> programs are fully
compatible over the available platforms, except that some (almost
exclusively obscure) features may have a different or have no effect on
some implementations.
<P>The implementation of all of <font size=-1>XPCE</font> on top of its
primitive graphicals guarantees there are no platform-specific
limitations in the manipulation and semantics of certain controllers. <font size=-1>XPCE</font>
defines the look-and-feel for each of the controllers. As a consequence,
<font size=-1>XPCE</font> controllers may not behave exactly the same as
controllers of other applications in the same windowing environment.
<P>All good things come at a price-tag and portability based on a
virtual environment is no exception to this rule. <font size=-1>XPCE</font>
builds high-level controllers (called dialog-items in its jargon) on top
of the virtual machine and therefore bypasses the graphical libraries of
the hosting system. The same technique is used by many other portable
GUI toolkits, among which Java.
<P>The visual feedback (look) and to some extend the reactions to user
actions (feel) of the <font size=-1>XPCE</font> controllers is
determined by
<font size=-1>XPCE</font>'s <EM>defaults</EM> file, located in
<CODE><<VAR>pcehome</VAR>>/Defaults</CODE>. See <A class="sec" href="classvar.html">section
8</A>.
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