Transparent windows, possibilities?

[Yogesh M]

Hi

I want to have my Qt4 app's window be partially transparent (i.e. some
parts have variable transparency), just like Qt does it for widgets
(using backing-store).

AFAIK Qt4 doesn't provide somethink like this, so I've to do something
on my own (using X directly). But I've no experience working with Xlib
and just have a rough idea about how X works.

Do someone has an idea about what should be done?

Somewhere in my mind is this idea: Use composite for a screenshot of
each window and blend with my window. This, for me, looks like very
ugly idea (and perhaps would be slow), but I've no idea of how
composite functions or what it can do or not.


Someone has done similar in qtclock
(http://www.linuxlots.com/~siraj/qtclock.html) to display shadows,
which stops working as soon as compmgr is turned off. May be, there is
some loop-hole left in the application, but having no experience with
composite/xrender, I can't figure it out. (It'll be great if someone
can look at code, pointed to above. It is really short one.)

Waiting for your help...

-- 
Yogesh M
Chandigarh, India