[Bug 40474] Popup menus no longer close when clicking on a different window

https://bugs.winehq.org/show_bug.cgi?id=40474

--- Comment #3 from Vincent Povirk  ---
There are message tests showing that capture is set at this time, but the
capture needs to be set on the owner of the popup window for the tests to pass
(not currently possible because of the X11 limitation). This particular patch
wasn't needed to fix a specific bug, I was just trying to make Wine's behavior
as close to native as I could.

I was working on a specific bug, but the fix didn't require this change.