Add a Button to the form and in the Click event, place the following Code:

WITH THISFORM.MyGrid && I assume this is the name of your grid
lnWidth = .Width
lnHeight = .Height

lnFormH = THISFORM.Height
lnFormW = THISFORM.Width
Thisform.windowState = 2 && This maximises the form

.Width = THISFORM.Width*lnWidth/lnFormW
.Height = THISFORM.Height*lnHeight/lnFormH
ENDWITH