Display 1 buttons stuck after click until non-button used or other display gets focus

[Harry Coin <hcoin quietfountain com>]

Hello!

I've a mid-sized, debian/squeeze (2.18 gtk family) , amd64, 
multithreaded, gstreamer (webcam in a small window), gdk ,  two display 
gtkbuilder 2.0 application that worked well under debian/lenny 
(stable).   Moving to 'squeeze' / testing a very weird effect happens.  
Display 1 is fullscreen, 0 is in a window. Display 1 has a webcam image 
and a table of four rows, four columns that holds a number of  on/off 
buttons and simple click buttons.  

After the change from lenny, any of these buttons  will accept one 
click, send the event signal to the right handler relative to the click, 
the appropriate of the various handlerer returns after doing the right 
thing -- but then gtk simply will not accept further clicks (but allows 
normal mouse movement and will show the focus change on a click attempt) 
until either:  a combo box on display 1 is changed, or the mouse is 
moved even for a moment off display 1 onto 0, then back on to 1 (without 
clicking anything on display 0).  After either of those things, the 
toggle buttons will allow one more click, and the cycle repeats.  \

In all ways the application is normal after hours of use -- except 
having to slide the mouse off display 1, on to 0, and back onto 1 before 
any further button (single or toggle) within the table on display 1 (of 
2) will accept a further click.  The application responds normally in 
all other respects.

How odd is that?  Any ideas?