March 29, 2001, 3:55 PM —
GTK+ is an acronym for the GNU image manipulation project (GIMP) toolkit. Spencer Kimball and Peter Mattis began work on GIMP in the summer of 1995. The first versions of GIMP relied on Motif, which was the dominant commercial standard for Unix GUI development over the last decade, as we explained in an earlier report in this series on GUI toolkits.
However, Kimball and Mattis wanted GIMP to be entirely free, and Motif's license was quite restrictive at the time. They decided to recraft GIMP as a free, general-purpose GUI toolkit, the first version of which they released as GTK in July 1996.
So one of GTK+'s distinctions has always been its license. It's a solid member of the GNU project, available under the GNU Lesser General Public License (LGPL). This may be the feature that developers mention most often when explaining their choice of GTK+. Many programmers now actively seek out licenses such as LGPL, instead of Motif or other toolkits.
The force of the license argument has diminished since GTK+'s birth. Qt's license has been liberalized, and Motif's source code is now available in some situations. There are even a few situations -- mostly concerning Linux-based embedded systems -- where the GTK+ license is inconvenient for proprietary-software developers. It is more common, though, for an organization to prefer Motif or Qt because of their restrictive commercial licenses.
GTK+ speaks in many tongues