Thanks. Actually I found a better solution for myself. I'm just doing
Lua Code:
--fix for button1 placement with only one form
StanceBarFrame:ClearAllPoints()
StanceBarFrame:SetPoint("BOTTOMLEFT",frame,cfg.padding-12,cfg.padding-3)
StanceBarFrame.ignoreFramePositionManager = true
The StanceBarFrame will get moved via the position manager. But we can disable that behaviour. Now we only need to adjust the offset for button1. (Offset is found in FrameXML/stancebar.lua)