Xemacs
Xemacs
(text, tool)Lucid chose to build part of Energize, their C/C++development environment on top of GNU Emacs. Though theirproduct is commercial, the work on GNU Emacs is free software, and is useful without having to purchase theproduct. They needed a version of Emacs with mouse-sensitiveregions, multiple fonts, the ability to mark sections of abuffer as read-only, the ability to detect which parts of abuffer has been modified, and many other features.
The existing version of Epoch was not sufficient; it did notallow arbitrary pixmaps and icons in buffers, "undo" didnot restore changes to regions, regions did not overlap andmerge their attributes. Lucid spent some time in 1990 workingon Epoch but later decided that their efforts would be betterspent improving Emacs 19 instead.
Lucid did not have time to get their changes accepted by theFSF so they released Lucid Emacs as a forked branch ofEmacs. Roughly a year after Lucid Emacs 19.0 was released, abeta version of the FSF branch of Emacs 19 was released.Lucid continued to develop and support Lucid Emacs, merging inbug fixes and new features from the FSF branch as appropriate.
A compatibility package was planned to allow Epoch 4 code torun in Lemacs with little or no change. (As of 19.8, LucidEmacs ran a descendant of the Epoch redisplay engine.)