Subject: FVWM: menu in overlay planes

From: Frederic Devernay <[email-masked]>
Date: Tue, 21 Nov 1995 15:39:58 +0100

SGI X servers don't provide the save-unders server option, thus
whenever a Fvwm menu is drawn, the contents of the display under it is
lost and must be redrawn. It can take a lot of time, e.g. if it's a
large 3-D scene.

SGI servers provide an alternative to it called Overlays, which
consists of a completely different visual with a small screen depth
(usually 2 bits), which is drawn over everything else, and it would be
great if fvwm could use this feature whenever it's available. The only
problem is that since Overlay planes have a small colormap (3 colors +
transparent color), we will have to reduce the color usage for menus
(black + white + menubackground) and use pixmap for shaded borders
instead. GLUT (http://www.sgi.com/Technology/openGL/glut.html) uses
Overlays for its menus whenever it's available.

Is anybody else interested in this extension of fvwm?

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---

From: Mark Powell <[email-masked]>
Date: Wed, 22 Nov 1995 09:51:18 GMT

> From: Frederic Devernay <[email-masked]>
> 

Yes.

I am responsible for providing X servers on the graphics hardware that
my company manufactures. I have been considering doing something like
this on hardware which has overlay planes, but for some reason they are
unused.

I don't know how SGI implement it, but the most likely would be that
the overlay planes are represented by different visual. Thus any windows
created with this particular visual appear in the overlay planes. At
least, that is how I imagined doing it. I don't think that would be too
difficult to incorporate, we just need an config option to specify an
alternative visual for popup menus.

I think some sun framebuffers might have other planes available too.

-- 
Mark Powell, Senior Software Engineer <[email-masked]>
Primagraphics Limited, Graphics Court, Melbourn Science Park,
Melbourn, Royston, Herts SG8 6EJ, England. Tel. +44 1763 262041
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