X application ignoring the keyboard and mouse

[Remus]

Hello everyone,

I have an application which captures both the keyboard and the mouse.
All the time, this application is on top of any other X app.

Usually, this application is translucent, allowing the user to see through it.

At some point in time, this application should be "translucent" to keyboard, and mouse events, too.
So, if xcalc is behind it, any keyboard/mouse events need to be intercepted by xcalc, as if my app 
does not exist at all.

Now, for the keyboard, the problem can be solved somehow, by setting xcalc to be the focused window.
But for the mouse, I did not found a good solution.

One solution would be to use XTestFakeKeyEvent & XTestFakeButtonEvent calls.
But if instead xcalc I have a drawing app, for example, which uses drags, Ctrl+Mouse, and so on, this 
turns to be too complicated.

Using the shape extension is not a good solution, because the masked area will be completely translucent.

Any ideas, or directions to point to?

Thank you for any response,

Best regards,
Remus