Windows: Error dialog won't disappear

[rrrlasse]

If you edit an int field into something invalid (like "aaaaa"), a message box pops up with options "Leave without saving" and "Keep editing".

If you click "Keep editing", the dialog closes and re-opens. You can keep clicking "Keep editing" forever, it never goes away.

If you click "Leave without saving", the dialog also closes and re-opens again. But the second time you click, it disappears finally.

If you click the "X" on the window, it also disappears and re-appears, in an infinite loop.

[kraenhansen]

This relates to #3