[474030] Fix SWTException when CompareDialog is canceled

Check if the control is disposed before accessing it in
'refreshTitle()'. This avoids SWTExceptions when a CompareDialog in
which at least one difference was accepted or rejected is canceled via
the 'Cancel' button.

Bug: 474030
Signed-off-by: Stefan Dirix <sdirix@eclipsesource.com>
Change-Id: I913ea5e97eae0343b3f1601cfb893a861b55f9d4
1 file changed