[Visualpython-users] GTK issues and history

[Bruce S. <Bru...@nc...>]

Technical note for the technically interested, related to the intent to 
eliminate dependence on the GTK libraries for Windows and Mac:

GTK is a library for the C language for creating windows and handling 
events, especially on Linux. GTKMM is a "wrapper" of GTK for use by C++ 
programs. Because there exist Windows versions of these libraries (and 
Mac versions for the Unix-based X11 windowing system, as distinct from 
the native Quartz graphics), Jonathan Brandmeyer originally wanted to 
use GTKMM for Windows as well as Linux, and for X11 on the Mac, as this 
would mean that one set of code would work on all platforms. However, 
shortly before he left the project, he came to the realization that it 
was so incredibly difficult to install GTKMM  libraries on Windows that 
few developers would ever be able to build Visual on Windows. For that 
reason he rapidly wrote a Windows-specific module for creating a window 
and handling mouse and keyboard events.

The beta version of Visual 4 seemed to be significantly more buggy on 
Windows than on Linux, so when I started working on Visual this past 
fall I made the attempt to go back to using GTKMM, with the thought that 
perhaps the problem was with the Windows-specific code which Jonathan 
had created at the last minute. As it happens, his Windows-specific code 
seems basically fine, but this was masked by a variety of other problems 
which happened to be more visible on Windows than on Linux, which I 
worked on, one after another, as slowly the beta version worked better 
and better on Windows. I went through enormous difficulties, with blood 
all over the floor, to create a GTKMM build environment on Windows. This 
hair-raising tale is told in an article that you can read in the section 
"For developers" at vpython.org.

When David Scherer recently became interested in working on Visual 
again, he quite sensibly reacted in horror to the great complexity of 
the gtkmm build environment on Windows and proposed going back to using 
Windows-specific code. Having seen that many of the supposedly 
Windows-specific problems with Visual 4 were independent of the 
Windows-specific code (which I wasn't using), I was quite willing to 
agree that we should try abandoning the gtkmm approach on Windows. The 
non-gtkmm version seems to work as well or better than the gtkmm-based 
version, and it is far less complex. It can be easily compiled using 
Microsoft Visual Studio (and there is a free version of this available 
from Microsoft).

Moral of the story: Good people have volunteered a lot of time to the 
attempt to create an open-source cross-platform windowing system to 
support cross-platform graphics-oriented programs. Nevertheless, the 
existing gtkmm environment is off-scale complex, large, fragmented, 
inadequately documented, and incomplete on some platforms. It started on 
Linux, where it is the workhorse. But the ports to Windows and Mac are 
just plain too hard to use.

Bruce Sherwood