.NET: Debugging Designer Features of a Custom Control in Visual Studio

If you are creating a .NET custom control that has designer features, you may need to debug how that control works in the Visual Studio designer. It may seem weird, but when a control is in the designer, the code is running! The constructor is called, and events are being triggered. You may have bugs in your code, or need to understand what code is being hit when certain actions are being performed in the designer.

The trick to debugging a custom control is fire up a second instance of Visual Studio. Open the project that has your custom control in it. Then attach the second instance of Visual Studio to the process running the first instance of Visual Studio. You do this from the Attach to Process menu item on the Debug menu. In this dialog, the program name of Visual Studio is "devenv"; select it and click Attach. Then when you use the designer in the first instance of Visual Studio, it will hit any breakpoints you set in the second instance.