Bug 442769

Description of problem:
Double-Click mouse clicks do not work in Motif-based applications under
GNOME/Metacity when the "Select Windows when the mouse moves over them"
preference is enabled.  The bug is reproducible with a simple
Xt/Motif program available at the link below.

Version-Release number of selected component (if applicable):
metacity-2.16.0-10.el5

How reproducible:
always

Steps to Reproduce:
1. Launch test program
2. Single Click on displayed button and observer terminal output
3. Double Click on displayed button and observe that terminal still displays
   the words "Single click"
4. Perform same tests after disabling "Select Windows when the mouse moves over
them"
and observe the double-clicking on the button produces the words "Double click"
in the terminal window.

Additional info:
Test program is available at

http://www.ecs.csun.edu/~renzo/cs585/Heller.book/Volume6/ch11/multi_click.c

Compile as:
 gcc -o mc -c multi_click.c -lXm -lXt -lX11 -L/usr/X11R6/lib

Everything works perfectly when running with click to focus.

From Soren --
Some preliminary results:
- This bug is caused by spurious crossing events that causes Xt to think
  that the pointer left the button between the two clicks.

- My guess is that this is related to metacity having a passive grab on
  the window in focus follows mouse mode.

This is a pick-your-poison situation.

Metacity can either have an XGrabButton on the window, or not. If it does, then
crossing events will be generated, and we will see this bug, which is
essentially gnome bug 102209 [1]. If it doesn't, then it has no way of
intercepting clicks on the window which means that it can't focus or raise the
window in response to clicks. 

The reason it works in click-to-focus is that in that case metacity drops the
XGrabButton when the window is focused. We could do the same in sloppy mode, but
then a user could alt-tab focus some other window and then have no way to focus
the window again, except mousing out and back in. See gnome bug 115072 [2].

I believe any window manager will have the same problem, and that the only real
fix is to add an extension to X that would allow XGrabButton without clicks
causing crossing events.

References:

[1] http://bugzilla.gnome.org/show_bug.cgi?id=115072
[2] http://bugzilla.gnome.org/show_bug.cgi?id=102209

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+++ This bug was initially created as a clone of Bug #184143 +++