Calling blockUntilOperationsFinished() from tool event handler makes
KisShortcutMatcher to be entered recursively. It basically breaks events
flow and makes KisShortcutMatcher crazy.

I tried to move blocking into the shortcuts matcher itself (so that
it could treat recursive entrance correctly), but it doesn't handle
special cases like KisToolTransform::activate(), which should also
block (if we keep them blocking).

CCBUG:409275