How to: Keep a Windows Form on Top
Starting with the Microsoft Windows 2000 operating system, a top-most form always stays in front of all windows in a given application. In Microsoft Windows 98, a top-most form stays in front of all windows in all applications. For example, you may want to keep a floating tool window in front of your application's main window. The TopMost property controls whether a form is a top-most form. A top-most form will always float above other, non–top-most forms even when it is not active.
The dialog boxes and menu commands you see might differ from those described in Help depending on your active settings or edition. To change your settings, choose Import and Export Settings on the Tools menu. For more information, see Customizing Development Settings.
To make a form the top-most form in a Windows Forms application at design time
In the Properties window, set the TopMost property to true.
To make a form the top-most form in a Windows Forms application programmatically
In a procedure, set the TopMost property to true.