UPDATE  GuiFile GadID  Value

  This command will update the specified gadget to display the 
  new value you have specified.

  GuiFile    - The name of the GUI file the gadget resides in.

  GadID      - The  ID number  you have given to the gadget 

  Different gadgets have different update values you must give, 
  as follows :

  xButton    - No update
  xCheckbox  - 1 = Checked, 0 = Unchecked
  xSlider(s) - New current level of slider
  xListview  - New line number           - 1st line is line 0
  xRadio     - Number of chosen button   - 1st choice is No 0
  xCycler    - Number of current choice  - 1st choice is No 0
  xTextIn    - New Text
  Text       - New Text
  xTimer     - New Time/Interval - will also re-start the timer
  xNotify    - Name of new file/dir
  xHotKey    - New HotKey combination

  xTextBox   - New text - note that when the textbox is redrawn
               by update, it will cover any other gadgets that may
               be overlayed on it!

  Example :

  For a xTextIn type gadget in file MyGui.gc, having an ID of 3 :

  > Update  MyGui.gc  3  "New Text"

  For a Cycler type gadget.. make the 3rd choice the current one. 

  > Update  MyGui.gc  5  2