@Markus W What was the problem, and how did you solve it? Don‘t keep those of us reading with baited breath in suspense …!
Sorry I don't mean to tease, I forget that I know where I do things but others don't when I post a whole test project :)
Inside Window1.Resizing I added the Refresh(false) line to the end after the width and height changes. I guess the framework is then told to perform a refresh with without blanking the background which stops the flicker (so it was a framework issue after all). I use this "hack" a lot since the framework windows update to do things like correcting the rendering of containers while scrolling etc.
@Markus W Btw it probably should be
Public Function SetWindowPos(hWnd As Integer, hWndInsertAfter As Integer, X as Int32, Y as Int32, cx As Int32, cy As Int32, uFlags As UInt32) as Integer
Declare Function SetWindowPos Lib "User32.dll" (hWnd As Integer, hWndInsertAfter As Integer, X as Int32, Y as Int32, cx As Int32, cy As Int32, uFlags As UInt32) As Integer
Return SetWindowPos(hWnd, hWndInsertAfter, X, Y, cx, cy, uFlags)
Oh crikey, if you're running this on mac then lookout ;) I've done zero crossplatform testing of this code as its just thrown together mainly from code that I've worked on in the past which might not even not cope with 64bit :) Test test test, don't just cut and paste :) ;)