The problem I'm facing is indeed petty, but I hope that help in my
trying to resolve it will be more widely useful.

To take a break from work and to refresh the mind I run a copy of
Klondike from aisleriot. Suddenly for no apparently reason it
ceased to function properly. When I click on a card it greys out as it
shoud but I cannot then move it with the mouse. The greyed out card
stays in place.

If the problem were with the X system I assume it would show up
elsewhere. I reinstalled aisle-riot. It affects all aisleriot games
that require dragging, and so apparently it is a gtk problem. How does
one troubleshoot a misbehaving graphical application?

I played with gdb without really knowing what I was doing.

--
Haines Brown