“Years ago, the most important X toolkit was called Motif. Motif
was the core of almost all commercial and many non-commercial X
applications. This was a significant problem, because Motif was
until recently proprietary software in every sense of the word:
source code was unavailable, and the so-called “Open Group” was
unresponsive to developers and end users. The only free alternative
to Motif, Lesstif, was inadequate at the time to compile any but
the most simple applications. At the time, a huge amount of
rhetoric was being spilled over the subject.”
“In fact, Motif was one of the first major obstacles to the
progress of Linux in general. It was the most advanced toolkit
of its time, and thus many applications were coded against it.
Coding a replacement for Motif was an enormous undertaking.
Other toolkits (QT, for instance) were either facing similar
problems with licensing, or incompleteness, or simple technical
inflexibility or lack of publicity.“
“Among the incomplete toolkits, however, was a relatively
obscure one gaining developer mindshare very quickly. The toolkit
used to create the GIMP, then the most successful and high-profile
Linux application, then and still one of the crown accomplishments
of the Linux community, was spun off into a separate toolkit. Over
time, GTK+ gained much of the functionality it required to form the
foundation for a major X toolkit.”