Slow Window Drag Causes Transparent Window And Locks GUI

[Nathan Royce]

Originally submitted to KDE: https://bugs.kde.org/show_bug.cgi?id=390116
It was suggested that it was an x-server issue.

The short of it is this... If my system is under heavy load and I try
to drag a window such as chrome, the window starts off by changing
into transparent drag-mode and is slow to start to drag and at some
point I think loses my mouse and remains in that transparent-drag
mode.

At this point I'm no longer able to click on anything, but rendering
still works fine in this state.

The keyboard seems to work "somewhat" as well...
While I'm unable to alt-tab or alt-f4 I think, I am able to
CTRL-Shift-ESC and switch tty. Once I force the offending program to
quit (not xorg stuff, but the window I was dragging), everything goes
back to normal.

I suggested that maybe periodically poll the mouse state instead of
relying on an interrupt/event that may not be caught in cases like
this.