In an embedded Linux system, I'm trying to show a shutdown notification that should override any other windows when shutting down. Now creating the window isn't a problem, but showing the window reliably is. The X server or WM is somehow too busy to draw the notification every time. Considering the limited CPU power we have, its not surprising.
So, I figured I will make it easy to the WM/X by grabbing the X server using gdk_x11_grab_server() (which calls XGrabServer on default display). But when should I call the grab func? If I call it before building my window, prior showing my window or event in expose-event of my window, nothing is drawn to the screen (even in no-load test)!
The documentation says:
The XGrabServer function disables processing of requests and close downs on all other connections than the one this request arrived on.
I suppose that would mean that only requests from my app should be processed, but it seems that is not the case, since nothing is drawn if X is grabbed by my app.
So, how and when should grabbing the X server be used to achieve wanted outcome, or is it totally a wrong tool and I've misunderstood the use (or trying to use it too high level for it to work really).