Try this:

_screen.TitleBar = 0
SET SYSMENU OFF
SET SYSMENU TO
_screen.WindowState = 2
oTimer = CREATEOBJECT([MyTimer])
oTimer.Enabled = .t.
READ EVENTS
_screen.TitleBar = 1
SET SYSMENU TO DEFAULT



DEFINE CLASS MyTimer AS Timer
  Interval = 3000
  Enabled = .f.
  
  
  PROCEDURE Timer
      CLEAR EVENTS
  ENDPROC
ENDDEFINE

And you will see that when _screen goes maximised it covers the task bar.
Is there a way to make it behave normal :-))).