编写一个可变颜色的标签，用一个按钮控制颜色的改变与停止。点击按钮颜色停止变化，再点击该按钮颜色又开始变化。-The preparation of a variable color labels, using a button control to change the color and stop. Click the button to stop the color change, and then click on the button to change the color again.