Some time ago, Andy Piper wrote...
I'm undoing Kirill's change to image_instance_layout as it
causes much
lossage with the tabs. Hopefully
we can figure out the correct fix. 
I agree - this was a kind of "experimental part".
-  XIMAGE_INSTANCE_DIRTYP (image_instance) = 0;
+  /* Do not clear the dirty flag here - redisplay will do this for
+     us at the end. */ 
Dice it will! The flag newer goes off, that's what I tried to fix.
Big K