Sams Teach Yourself Microsoft® Visual C#™ .NET in 24 Hours

Adding an Invisible Control to a Form

All of the controls that you've used so far sit on a form and have a physical appearance when the application is run. Not all controls have a physical appearance, however. Such controls, referred to as nonvisual controls (or invisible-at-runtime controls), aren't designed for direct user interactivity. Instead, they're designed to give you, the programmer, functionality beyond the standard features of Visual C# .NET.

To allow the user to select a picture to display, you need to give her the capability to locate a file on her hard drive. You might have noticed in the past that whenever you choose to open a file from within any Windows application, the dialog box displayed almost always looks the same. It doesn't ...