Path: utzoo!censor!geac!jtsv16!uunet!mcsun!sunic!luth!eru!bloom-beacon!ATHENA.MIT.EDU!swick
From: swick@ATHENA.MIT.EDU (Ralph R. Swick)
Newsgroups: comp.windows.x
Subject: Re: Novice question
Message-ID: <8909071536.AA00935@LYRE.MIT.EDU>
Date: 7 Sep 89 15:36:07 GMT
References: <110@euteal.ele.tue.nl>
Organization: DEC/MIT Project Athena
Lines: 25

> How can I get an ordinary window into the widget
> hierarchy? Ordinary means: a window in which I can draw
> using the Xlib primitives.

You can't insert an existing plain window directly into the
widget hierarchy; it needs a "widget wrapper" around it to be
understood by the rest of Xt.  Any window created by any widget
is "ordinary" in the sense that any Xlib primitive works on it;
that's how widgets 'do their thing'.

There are numerous ways to get a widget set to create a window
for you into which you can draw (i.e. without interfering with
any drawing that the widget may be trying to do).  Some widget
sets have a "Canvas" or "Window" widget expressly for this
purpose but they typically do much more than you want or leave
out something of importance (such as a third pixel value, etc.).

At the most basic level, you can simply create an instance of
the Core widget.  The class name for Core is just widgetClass. 
You can then register event handlers on this widget to handle
such things as Expose.  If you want Xt to automatically get
resources for you and compress exposure events as it does for
other widgets, then you should read the last section of the
Athena Widgets manual and modify the Template widget to suit
your needs.