Temporary fix concerning planar figures and MxN
Summary: Skip rendering of planar figures in windows that are not from StdMultiWidget, see my latest comment in T29333 .
Test Plan: Draw some planar figures in the StdMultiWidget view using the Measurement view. Switch to MxN. None of the planar figures should be visible, even when at the correct location.
Reviewers: O1 MITK Reviewer Group I, kislinsk
Reviewed By: O1 MITK Reviewer Group I, kislinsk
Subscribers: kislinsk, kalali
Differential Revision: https://phabricator.mitk.org/D801