Enter the number of glass panes in the frame, usually 1.
The button to the right of the Glass Box allows you to select a different type of glass from a drop-down list (or use Alt-G). Note that the glass type will always revert to the default glass type after the job has been cleared.
The descriptions and prices of the various types of glass you use may be defined in the Options/Prices screen.
You can set the default type of glass (the type you use most often) in the Options/General screen
Note that if the dimensions exceed the standard size then the program will issue a warning.