On oreo (fc5):
IDL> help,/device
Available Graphics Devices: CGM HP LJ NULL PCL PRINTER PS REGIS TEK X Z
Current graphics device: X
    Server: X11.0, The X.Org Foundation, Release 70000000
    Display Depth, Size: 24 bits, (1600,1200)
    Visual Class: TrueColor (4)
    Bits Per RGB: 8 (8/8/8)
    Physical Color Map Entries (Emulated / Actual): 256 / 256
    Colormap: Private, 16777216 colors.  Translation table: Enabled
    Graphics pixels: Decomposed,        Dither Method: Ordered
    Write Mask: 16777215 (decimal) ffffff (hex)
    Graphics Function: 3 (copy)
    Current Font: <default>,    Current TrueType Font: <default>
    Default Backing Store: Req from Server.

On sofie (fc7):
IDL> help, /device
Available Graphics Devices: CGM HP LJ NULL PCL PRINTER PS REGIS TEK X Z
Current graphics device: X
    Server: X11.0, The X.Org Foundation, Release 10300000
    Display Depth, Size: 24 bits, (1280,1024)
    Visual Class: TrueColor (4)
    Bits Per RGB: 8 (8/8/8)
    Physical Color Map Entries (Emulated / Actual): 256 / 256
    Colormap: Private, 16777216 colors.  Translation table: Enabled
    Graphics pixels: Decomposed,        Dither Method: Ordered
    Write Mask: 16777215 (decimal) ffffff (hex)
    Graphics Function: 3 (copy)
    Current Font: <default>,    Current TrueType Font: <default>
    Default Backing Store: Req from Server.