I noticed while building wxWidgets library on linux or FreeBSD that wxWidgets required other GUI libraries such as GTK+, Motif etc. whereas the GTK+, Motif or FLTK libraries are seem to be independent as they don't need any other GUI libs.
Although these libs need xlib but we don't have to do anything with xlib.
I don't understand it.
wxWidgets does its best to keep the OS look & feel (read: appearance and behaviour). For example on Windows wxWidgets uses the controls that Windows provides. Same for Apple OSX. Here is where the word "native" is meaningful.
On Linux there are several "desktops" (that provide the controls): GTK+, KDE, etc. wxWidgets uses only GTK+ (the old Motif is not used anymore), and so GTK+ provides the "native" controls. Note that the desktops use underlaying Xlib or Wayland.
When some control is not available in a platform (e.g. 'data view') then wxWidgets uses its own, generic, control. This generic control usually is made of a composite of native controls, so the look and feel is kept.
The opposite is Qt, which only uses very "deep and basic" features of the OS, such as drawing. This way, the appearance of the controls is the same in all platforms.
