Image on disabled button

[Richard Townsend]

> 
> (From memory) the following options added after creating the root window
> prevent the bug occurring on HP-UX11i
> 
> self.root.option_add('*background', 'grey75')
> self.root.option_add('*disabledBackground', '')
> 

I have now checked again on HP-UX and have found that you must also set:

self.root.option_add('*disabledForeground', '')

to stop the bug appearing...