https://developer.gnome.org/pygtk/stable/class-gdkwindow.html
http://nullege.com/codes/search/gtk.gdk.Pixmap.cairo_create
http://www.pygtk.org/docs/pygtk/class-gdkdrawable.html
http://blog.csdn.net/shenbin1430/article/details/4580532
http://zetcode.com/gui/pygtk/drawing/
个人学习查找资料，作为备份。