o add tab widget
o add file browser widget
o add opengles backend
o port to android
o port to rt-thread
o port to wince
o port to iphone
o more documation.
o multi font size supported.
o re-implement window animation.
o performace and memory optimization.
o use gb2312 font to replace unicode fnt.
o use google pinyin as default input method.
o re-create vs2008 project, and port desktop to windows.
o re-implement default font to minimized the memory size.
o change font_canvas to interface, so it can be optimized on different
platform.