显示鼠标位置，当鼠标进入窗口时，用一个文本框给出鼠标进入或离开的信息，当鼠标左键按下拖拽时，文本框给出鼠标所在点的坐标。-When the mouse entered the window, when the mouse entered the window, with a text box to enter or leave the information, when the left mouse button press and drag, the text box gives the coordinates of the mouse.