说明：  创建异形窗体函数 SetWindowRgn 放到合适的位置，别让拖动窗体改变大小时出现用做 MASK 的紫色区域；再者与大家分享不指定窗体风格 WS_THICKFRAME（对于对话框，相当指定其属性 Border 为 Resizing ）,用代码实现窗体拖放，任意改变其尺寸。
(SetWindowRgn function to create special-shaped form on the right position, Do not change the size of form drag occurs when MASK used to do the purple region In addition to share with you do not specify a form style WS_THICKFRAME (for the dialog box, specify its properties rather Border for Resizing), using drag and drop code form, arbitrary change its size.)