c#程序的设计理念之一是向后兼容性，有利于版本的升级，和应用程序的可移植。这是一个画图程序，仿照微软的画图功能制作。旨在体现这一点。-c# procedure design concept is one of backward compatibility, there is in favor of versions of the upgrade, and applications can be transplanted. This is a Paint program, modeled on M