drawing on X11, above all applications, emulating an alpha channel

[Ana <christiana hipointcoffee com>]

Hi.

I've been messing around with my little ir remote control recently,
having fun...   and I've been, sort of, longing for some way to make the
current "tv-channel" show up on my screen in the upper right hand corner
of my monitor.  You know?  Like my TV displays the new channel number
for 1 or 2 seconds after I press, for example, the channel-up button.  I
want to see the numbers up on the screen above any and all other
applications.  I don't want to have to rely on an application (like
mplayer) running in full-screen mode in order to do this.

So, I've been wondering how to look for an application that already does
this.  And, I wonder how to make something like this happen, (which is
much more fun of course).

How to do it?...  I will have to experiment because I'm not sure what
problems I will run into.  So far, my basic idea is this:

- grab a screen shot section at the location where I want to draw my
  numbers/graphics.
- paint the numbers/graphics into the screen-shot image
- create a gtk-window without window manager decorations.  (no wire
  frame, no title bar)
- fill the window with one widget, which simply displays the altered
  screen-shot image.
- show() the window at the exact location where I had taken the
  screen-shot
- close window after some timeout.


and...  if possible, update the image, from time to time, with whatever
X11 would be displaying if my application weren't there, in order to
emulate numbers/graphics painted over an X-level-alpha-channel.

the basic idea should be very simple, I think.

I would like to hear others' thoughts about this.  Especially, I want to
hear about similar projects that I might pull from, or use un-altered.

Thanks,

- Ana