This is the case. I'll have a look at MDiViewPage this evening. Thanks for your help.
Where do I find a description of what files do what? I mean where is documented what "MDi" means and what files cover the page view handling (to find out by myself that this is MDiViewPage)?
(For the Win installer, I e.g. created a visual documentation because this is drawn quickly and sometimes an image tells more than text: https://github.com/FreeCAD/FreeCAD/blob ... ucture.odg ) Maybe this could also be an option for TechDraw?