Timing 'race condition' crashes the interpreter on OSX

[bobr]

With the form shown here, if I move the mouse pointer quickly from top to bottom over these text boxes, the interpreter crashes and sends a bug report to Apple.

Screen shot 2011-09-19 at 11.10.48.png (17.18 KiB) Viewed 4191 times

The underlying code is:

Private Sub CurrentPAL_OnEnter()
if CurrentPAL.value <> "" then
ShowItem.Caption = CurrentPAL.value & " "
ShowItem.Visible = true
end if
End Sub

Private Sub CurrentPAL_OnExit()
ShowItem.Visible = false
End Sub

Private Sub PreviousPAL_OnEnter()
if PreviousPAL.value <> "" then
ShowItem.Caption = PreviousPAL.value & " "
ShowItem.Visible = true
end if
End Sub

Private Sub PreviousPAL_OnExit()
ShowItem.Visible = false
End Sub

Private Sub PreviousBAL_OnEnter()
if PreviousBAL.value <> "" then
ShowItem.Caption = PreviousBAL.value & " "
ShowItem.Visible = true
end if
End Sub

Private Sub PreviousBAL_OnExit()
ShowItem.Visible = false
End Sub


. . . . etc.

If the mouse is dragged slowly over the text boxes, allowing ShowItem to be visible and invisible cleanly, the error doesn't happen.

[bobr]

Just for "completion" this is NOT just an interpreter problem. It happens just the same with compiled code.