I have run into a potential Beta issue.
I have some 'PFC style' resize logic in a window wherein when its size is changed some ancestor code is run which loops through the control array of the window and triggers the resize event on each control.
Now the tabpage control does not have a resize event script but so what, it should just silently fail.
On a 64 Windows 7 machine the window works fine. On a Windows 8.1 machine PB stops working and shuts down.
Will post further information as it is revealed to me...
Matt