Complex sentence: FLTK is free software, licensed under LGPL with an additional clause permitting static linking from applications with incompatible licenses, and includes "fluid" ("FLTK User Interface Designer"), a graphical GUI designer.
Split into simpler sentences: FLTK is free software, licensed under LGPL with an additional clause permitting static linking from applications with incompatible licenses. It includes "fluid" ("FLTK User Interface Designer"), a graphical GUI designer.