Change font size in UnoControlGridModel

I've developed a Calc Dialog with several controls including the dynamic 
gridmodel control. The only font property I've been able to change 
successfully is GridModel.TextColor. Other font properties have no 
affect. Is there a specific syntax for setting the font size? I've tried 
several alternative property settings, but nothing seems to work other 
than the text color.

dlgmodel = oDialogInventory.getModel()
    gridmodel = 
oDialogInventory.getModel().createInstance("com.sun.star.awt.grid.UnoControlGridModel")
    with gridmodel
        .PositionX = 8
        .PositionY = 33
        .Width = 150
        .Height = 55
        .TextColor = RGB(255,0,0)
      end with

Thank you..........awm119