LessTif

By the mid-nineties Motif was the standard toolkit for commercial Unix software, but it cost money and couldn't ship with a free Linux distribution. A group calling itself the Hungry Programmers set out to reimplement the library from scratch against its API, under the LGPL. The name is a pun — less than Motif — and like the original it sat on top of Xt.

The target was source compatibility with Motif 1.2, and for plenty of programs that was enough: Netscape Navigator and a long tail of scientific tools could be built against it. The trouble was in the corners, where applications leaning on undocumented behaviour misbehaved in odd ways. Once the Open Group released Open Motif in 2000 and Motif went LGPL in 2012, the reason to exist was gone and the project went quiet. By then it had done its real job: keeping old software alive on Linux until GTK and Qt took over.