>>>>Any ideas on what would cause the form close button to become disabled during normal data entry operation with a modeless form? The form seems to be otherwise fully functional, can change pages in pageframe, can select another form, can minimize the form, menu options are functional, etc.; just can't close it. Toolbar form close button is also disabled when that form is active. FWIW, some data entry on the page where this seems to occur is in a grid, but that remains fully functional as well.
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>>>Check also message #925618
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>>Thisform.Closable = .T. and that is never changed in code.
>
>Try to trigger it back and forth, that's what this message suggests.

Right, but this form works just fine 99% of the time. There is apparently some weird sequence of events that can occur to cause the problem. Without knowing what that is, there's no way to know where to put the trigger code.