QNX: Fix sending of expose events

When the window geometry is changed an expose event should only be sent
if the window is visible.

Change-Id: I540ea7e7e07d896495547f3f8bf81738fad3ddee
Reviewed-by: Bernd Weimer <bweimer@blackberry.com>
Reviewed-by: Sergio Ahumada <sahumada@blackberry.com>