Was able to figure out what caused that. This particular form contained ActiveX

and application.autoyield = .f.

To see splitter bar movemement I have to switch back to .t.

application.autoyield = .T.
_screen.ActiveForm.LockScreen = .T.


FOR lnObjCtr = 1 TO ALEN(this.Parent.aObjSplitMove)
this.Parent.aObjSplitMove[lnObjCtr].Move(5)
ENDFOR

_screen.ActiveForm.LockScreen = .F.
application.autoyield = .F.



>Originally just cut and paste all relevant code creating control from scratch but was unable to see it moving when it is being dragged , though MouseUp gave the same results regarding resizing. Ended up with the class copying and stripping some code and it started to work as expected. Just curious what actually determines visibility during MouseDown event.
>
>Thank you
>Michael