It seems that the MouseMove event of the grid is not triggering correctly when the user drags the hidden (.colwidth =0) column. Therefore we have to use an external event to set the colwidth to 0. So I've used a timer control. In the following example, the 3rd column is hidden. The flex grid name is msgDetails.

Private Sub Timer1_Timer()

With msgDetails

If .Redraw = False Then

.Redraw = True

End If

If .ColWidth(3) <> 0 Then

.Redraw = False
.ColWidth(3) = 0

End If

End With

End Sub