XTR'XVALIDATE was returning 1 instead of 2 when exiting for validation of checkboxes; this was fixed.
Note that XTR'XVALIDATE=1 means that the XTR'XROW/XTR'XCOL cell (i.e. the one we just left) needs to be validated; while 2 means that the XTR'TARGETROW/XTR'TARGETCOL cell needs to be validated (the one we just clicked or are navigating to). In the case of checkboxes, they exit for validation only when the checkbox value changes, which occurs immediately when you click, rather than when you move the cell focus (as would be the case with a normal editable cell). So if you are focused on a checkbox at 5,7 and you click another checkbox at 3,9 then XTR'XROW/XTR'XCOL will be returned as 5,7, while XTR'TARGETROW/ XTR'TARGETCOL will be returned as 3,9. But the checkbox that has changed is the one at 3,9 (the one clicked), so it is the one that should be validated.
