Do not send FocusChangedEvent when focus does not change
Summary: When the same renderwindow is clicked twice, the RenderingManager sends a new FocusChangedEvent each time. This is prevented with this patch.
Test Plan: Tested manually by debugging.
Reviewers: O1 MITK Core, kislinsk
Reviewed By: O1 MITK Core, kislinsk
Subscribers: kislinsk
Maniphest Tasks: T19820
Differential Revision: https://phabricator.mitk.org/D6