In order to work with the new multi widgets and editors several classes need to be refactored (remove `StdMultiWidget(Editor)` dependencies).
A lot of hard-coded `QmitkStdMultiWidgets` are used where an `MxNMultiWidget` should work, too.
Additionally the whole render window lay-outing needs to be revised in order to cope with the new multi widget.
IMPORTANT: This is a huge and mayor change that needs to be reviewed, observed and communicated with the userbase.
In order to fully use these changes, the following tasks need to be solved:
{T26542}
{T26543}
{T26545}