FMSLogo Code

Work around a problem that appeared on GNU/Linux after upgrading from wxWidgets 2.8 to wxWidgets 3.0.
For some reason, wxINVERT does not work in GTK (the lines it draws are invisible)

Update CScreen to work better with wxWidgets 3.X for GTK
* Change the super class to a documented type of wxScrolled<>.
* Change deprecated calls to PrepareDC to DoPrepareDC.
* Use m_DeviceContext.SetBackground() to set the brush for Clear()

Increase the minimum screen size from 200x200 to 400x400.

After upgrading wxWidgets from 2.8 to 3.0, the GTK default size no longer worked as before and a window size of 200 was clearly to small, as the commander width follows the screen width and 200 pixels is not large for the history and the buttons.

Fix a build break on non-Windows platforms caused by upgrading to wxWidgets 3.X.

This is not surprising, since the code had been relying on an internal
API that happened to be exposed by the DSO on Fedora. This revision updates
the code to use public API and it handles more cases (although it's still
not perfect).

Update the Linux portion of the Makefile to use wxWidgets 3.X

Fix a build break on Windows that was introduced by my previous change.

Fix two crashing bugs that were introduced on Unicode builds when wxWidgets was upgraded from 2.8.1 to 3.1.0. First was that "argv" stopped behaving like the ANSI C "argv" in that argv[argc] was invalid memory, instead of NULL.

Second is on debug builds, trying to print out all memory leaks crashed because a "const char *" can no longer be converted to a wxString after the atexit handlers have started to be invoked.

Convert the text control of the minieditor to be a CLogoCodeCtrl instead of a wxRichTextCtrl. This was done to add syntax coloring and matching paren highlights to the minieditor.

Fix a bug where the definitions from the minieditor would sometimes be replaced with garbage characters or possibly crash.

The bug has always exited, but the symptoms of the bug were brought about by the update to wxWidgets 3.1.0, which changed the implementation of wxString enough so the prodedure body that was read from the mini-editor would be freed before its buffer was copied into the reader. The fix is to hold a reference to the wxString while its internal buffer is being used.

Enable wxStatusBar so that menu items can be disabled.

This is a regression introduced after rewriting the configure script to start by enabling features used instead of disabling ones that weren't used. Since FMSLogo does not use wxStatusBar, it made sense not to enable it. However, as described in bug #423, there's a quirk of wxWidgets where it requires the status bar to send "update UI events" that are used to disable menu items.