MFC Button按钮的Owner draw属性 所有者绘制
允许自画
自画
可以改变按钮的形状和外观 如圆形按钮 ,动画按钮
BS_OWNERDRAW
Creates an owner-drawn button. The framework calls the DrawItem member function when a visual aspect of the button has changed. This style must be set when using the CBitmapButton class
