#385 Deleting window from creation callback has OWL exception

[David Costanzo]

If you invoke WINDOWDELETE from the context of the "callback" input to WINDOWCREATE, OWL throws an unhandled exception, which manifests itself as a message box that, if you press "No" on, will terminate FMSLogo.

Steps to Reproduce:
windowcreate "r "w "title 0 0 120 400 [ windowdelete "w]

What Happens:
You see the following error message box:
---------------------------
ObjectWindows Exception
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Create fail for window title, 0, TMxWindow
OK to resume?
---------------------------
Yes No
---------------------------

Pressing No results in an "abnormal termination" dialog box, followed by FMSLogo closing.

Expected Result:
Either the window is created and delete without incident, or FMSLogo throws a Logo error.

[David Costanzo]

This also affects the wxWindows version of FMSLogo.

[David Costanzo]

This is fixed by [r6154]. It will be available in FMSLogo 8.5.0.

The bug was more severe than the title or the symptoms suggest. This was a freed memory read. DELETEWINDOW deleted the window, then CREATEWINDOW dereferenced the deleted window object to try to show it. The fix is simple, after running the "setup" instruction list check if the window was deleted before trying to show it.