GtkWindowForms is lib for View-Layouting through gtk+/c++ it has many features included such as Floating/dockingViews, save/load layouts..etc. It cuurently tested under Win32 and Linux. Here a screenshot http://www.team-bytestorm.com/gtkwindowforms.jpg.
wxGraphicControls is a set of many customizable controls
...You are able to specifiy corresponding images which are shown in the specific state of the control.
- supports completly transparent looking controls
- loadable through wxWidgets-XRC-System
See screenshot for more information!