#604 Mac beta build crashes when stress applied

[Hal Crichton-Standish]

On the latest mac beta build, after setting up a simple sin graph and adding two godley tables, the program froze. In the top bar it reads: Minsky: -psn_0_315469

[High Performance Coder]

The psn_0_315469 display is ahem a feature of MacOSX. I don't really intend doing anything about it, as it is a cosmetic problem.

The more serious problem of the program freezing is due to a modal dialog being hidden behind the main application, and not closed, thereby preventing the main window from receiving events. The bug is really in the implementation of Tk's error modal dialog - the dialog needs to slaved to the main window via the wm transient command. This affects all X11 builds, not just macOSX. I have a solution to the problem, which involves overriding the tk::SetFocus proc to add the missing wm transient statement. Windows builds are unaffected by all this :).