On Jan 4, 2008, at 5:11 PM, Brian Heibert wrote: > Failed Assertion: > fn IsWRefConFBHandle (wRefCon) > at line 951 in RTM APPEARANCE.INCL In case I didn't make this clear before: Failed assertions are generated by the FB runtime and it typically means there is a bug in the user code. My thought about the window issue was related to the code shown (i.e. wRefCon) and a similar issue seen by Deb Lake late last year. This doesn't mean you have the same issue. Brian S.