Timer slack for slacker developers

Well, it's not that easy. Your window may be covered, except that the user presses Alt-Tab and expects to see current content (clocks, download managers, …). Or it may be covered by something that's almost, but not quite, opaque.

That's not the problem, though. The problem is that you can't depend on every program to get this right, but, on the other hand, you do need some way for a program to tell the kernel that when it says 0.2sec it MEANS 0.2sec and not something random that may be roughly of the same order of magnitude. Or not.

How exactly to do that is the kernel people's problem. New scheduler class, new kind of timer, whatever.