The IDL docs for XMouseClickHandler don't explain what the boolean return values
for mousePressed() and mouseReleased() do.

The docs for XUserInputInterception talk about consuming events, so I guess
that's what these return values are about, but I see no indication as to whether
true means "consume the event" or "pass on the event". The IDL for both
interfaces should be improved.

Interestingly, I've tried to find out what means what by registering 2 handlers
and returning either false or true from both after printing a message. I always
see both messages, so consuming the event (mouseReleased in my testcase) doesn't
seem to work. Is this feature implemented at all?