说明：

　　上、下：改变图形大小

　　左、右：改变图形形状

　　鼠标左键：在一点新产生一个图形（只能生成一个）

　　鼠标右键：取消新产生的图形-Descr iption: Upper and Lower: change the graphic size of the left and right: the shape of the left mouse button to change the graphics: The graphics create a new point (only to generate a) the right mouse button: the abolition of the new generated graphics