Path: utzoo!attcan!uunet!husc6!rutgers!apple!bloom-beacon!EXPO.LCS.MIT.EDU!jim
From: jim@EXPO.LCS.MIT.EDU (Jim Fulton)
Newsgroups: comp.windows.x
Subject: Re: Transparent windows?
Message-ID: <8809191507.AA01335@EXPO.LCS.MIT.EDU>
Date: 19 Sep 88 15:07:11 GMT
References: <24955@bu-cs.BU.EDU>
Sender: daemon@bloom-beacon.MIT.EDU
Organization: X Consortium, MIT Laboratory for Computer Science
Lines: 29


> A simple question:  Can you create a transparent window under X-Windows?

It depends on what you mean by "transparent window":

    1.  A window that has no background and which doesn't cause output to 
	other windows to get clipped (i.e. stuff drawn "beneath" the 
	transparent window still shows up even though it is "covered").

		Nope.  Not in the core X11 Protocol.

    2.  A window whose "contents" are never visible, but can still receive
	input events (more like "invisible" windows).

		Yes.  Create an InputOnly window using XCreateWindow.

    3.  A window that has no background but is used for clipping graphics.

		Yes.  Create a GC with a client clip region.


Note that these are all different from windows with background of None.
Setting a window not to have a background is simply an indication to the server
that you are going to fully repaint the window anyway and that it isn't worth
filling it with some arbitrary pattern.


						Jim Fulton
						MIT X Consortium