VC++ 实现的圆形旋钮，继续自slider,是学习重写slider控件的好例子。应用到开发中，极大的提高了用户交互的友好性！,VC++ to achieve a circular knob, to continue from the slider, rewrite the slider controls to learn a good example. Applied to the development, greatly improves the user-friendly interact

派生CSliderCtrl控件使其拥有新功能，可以同时选择多段数据。-you can select more than more area in the Slider