>TopLevel Form and Screen.visible=.F.

If you want to move the screen you really should leave the title bar. Otherwise, you can show it when you need it:

oForm = CREATEOBJECT('MyNoTitleBarForm')
oForm.Show(1)
DEFINE CLASS MyNoTitleBarFOrm AS Form
	titlebar = 0
	autocenter = .T.
	PROCEDURE mousemove
	LPARAMETERS nButton, nShift, nXCoord, nYCoord
	with this
		do case
			case nYCoord > 4 and .TitleBar = 0
			case nYCoord > 4
				lnWidth = .Width
				.Top = .Top + sysmetric(9)
				.TitleBar = 0
				.Width = lnWidth
			case nYCoord <= 4 and .TitleBar = 1
			otherwise
				lnWidth = .Width
				.Top = .Top - sysmetric(9)
				.TitleBar = 1
				.Width = lnWidth
			endcase
		endwith
	endproc
enddefine