Widget revision e53c48bf 
1What we need is a widget which presents a collection of buttons.  The user
2can select only one of them at a time.  When one is selected, its
3foreground and background colors should be reversed and stay that way
4until another one is selected.  Exactly one button can be selected at
5any one time.
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7Possible implementations:
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91.  As a new kind of widget.  bleah.
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122.  Box surrounding a lot of command buttons.  The command buttons have
13    the appropriate callbacks.
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15Callbacks:  a) set all buttons to normal colors
16            b) set this button to reverse colors
17            c) change the appropriate variable to the desired value.
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19    This can all be done at the time of creation, thus the buttons would
20    be invisible to the rest of the program (a good thing).
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24(2) would be a heck of a lot easier to program, since creating widgets is
25a bitch.  However, (1) could come in handy outside of this program.  Perhaps
26write it using (2) and switch to (1) if/when we can get the widget working.
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