I was trying to make a small test project, but I couldn't reproduce my issue.
In the small project it is working fine.
So I took a better look at the bigger project and I noticed the layout is not loading by loadlayout(..), but by AddView. Addview has width and height properties but it isn't scaling at resize.
I used addview in order to have the code of that layout in a different class.
'new layout in inner panel with code in class
Private Locations As Locations_c
Dim panLocations As Pane = Locations.initialize
PaneContent.RemoveAllViews
PaneContent.addview(panLocations,0,0,600,500)
I think I have to search a better way for handling multi layouts and a left menu column for my desktop application. Now I combined, B4Xpages, with drawer, and loading layouts in panels.
I think it is unnecessary complex now.