[colanderman]

Thank you for the detailed reply.

> Anything you do that changes the distribution of events (like moving the cursor in or out of a window changes the input focus, manipulating the window hierarchy changes the mapping from event position to window target, etc) needs to have its handler executed BEFORE any other events are distributed.

Yes, this is definitely a shortcoming of X. I have been thinking about this for some months; I believe that a solution which maintains the client-server model is to replace server grabs with transactions, which may be initiated by either the client or the server. Obviously this is not backward-compatible as it requires client support as well as server support.

[colanderman]

(Too late to edit post)

You can also achieve glitch-free focus-follows mouse using active input grabs. You don't even need to continuously grab them; you need only grab for the first event of each sequence of keyboard / mouse events.