You can use the form instance and set the property TopMost to True.
If you want to be over all Windows, there are another way with
Win32 Api calls.
Here is what you could do:
In your form class add :
[System.Runtime.InteropServices.DllImport("user32.dll")]
public static extern bool SetForegroundWindow(IntPtr hWnd);
In the form load you can add :
SetForegroundWindow(this.Handle);
This should do the trick.
Update
TopMost should do the job BUT: Top most OR/AND the Win32 Api call will only work not inside Visual Studio (well for Vista and with VS2008 I tested it... I can't tell for other). Try running the program with the .Exe from the /bin directory, it will works.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…