Can a program get the identifier of the XWindows root window? Assuming it can, are there any unexpected technical problems with designing 3D games/simulations/screensavers in OpenGL that draw on the XWindows root window (and receive its events)? Off hand, this way seems to have the least consumption of video-card resources by other processes than anything else.
In case it matters, these applications will be running on nvidia 7800 ~ 8800 generation graphics cards and beyond with VBOs, FBOs, GLSL shaders, and definitely need to take every advantage of video card capabilities (no software emulation!).
Is this the best/fastest way for fullscreen 3D applications? How much “hit” does an application take for creating a separate fullscreen window and overlaying the whole desktop?