实现自绘制标签按钮功能。本程序从CTabCtrl派生出一个CTabCtrlEx控件，用于实现标签控件的自绘制功能，让标签也五花八门吧!,Self-drawing button labels. This procedure CTabCtrl derived from a CTabCtrlEx control, label control for the achievement of self-mapping feature that lets you label a wide variety!