Get Desktop Deep and Herz

I need the screen deep and hertz from the actual Desktop Screen. I am working on a testprogram and the actual screen size and deep should be the same as the desktop. The height and the width work's great. Any idea's!

Code Sample:

For mode:TGraphicsMode=EachIn GraphicsModes()
width[i]=mode.width
height[i]=mode.height
deep[i]=mode.depth
herz[i]=mode.hertz
If width[i]=Desktop().width And height[i]=Desktop().height Then
AddGadgetItem combobox,width[i]+" x "+height[i]+" , "+deep[i]+" Bit , "+herz[i]+" Hertz",True
Else
AddGadgetItem combobox,width[i]+" x "+height[i]+" , "+deep[i]+" Bit , "+herz[i]+" Hertz"
EndIf
i=i+1
Next

But i need the deep and hertz, too.