[GNC] invisible checkboxes

[Graham Menhennitt]

Something very strange has happened to my GnuCash installation - I no 
longer have any checkboxes. In dialogs where I'd expect to see them, 
there is just blank space. In the reconcile window, when I hover my 
mouse over a line, I can see a blank white square where the checkbox 
would be. If I click the checkbox, the square changes to blue. But when 
I move the mouse away, it's invisible again. Other applications seem 
unaffected.

Does anybody have any suggestions, please.

Thanks,

     Graham