FLTK，如同其名字所表达的：The Fast Light Tool Kit，一个轻量级的GUI开发库。 Fl_DragBar是基于fltk写的一个可拖动的bar的控件-FLTK, as expressed by its name : The Fast Light Tool Kit. a lightweight GUI development library. Fl_DragBar is based on the FLTK can be written in a drag bar, the