添加*或在更改文本框的脏标志时更改背景（组框）颜色

I have a groupbox with a background of a certain color containing a textbox. I was thinking of ways to help the user see that the textbox was dirty, and thought perhaps changing the background groupbox color and/or adding a "*" to the name of the groupbox and/or Form Text would be nice. But I can't get the event to even change the property of _isDirty. Let alone implement this idea. I'm sure that someone has done something similar and Hope that you could help me. I'm working with C# .Net framework 2.0 (it should also work in 4.0 but that's backwards compatible I believe). IDE is Visual Studios 10.I have a groupbox with a background of a certai