如何在.NET中控制Windows应用程序焦点

Question

I'm using pinvoke "user32.dll" to send my application to back (behind all other apps) so it sits on desktop and vice versa. At the moment it just toggles - back/front. Is there a way to detect if my app is at the back and bring it to front or if it's on front and send it to back? THanks.

Answer 1

You can detect if your window is the active window by calling

[DllImport("user32.dll")] static
static extern IntPtr GetForegroundWindow();

You used to be able to call

[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool SetForegroundWindow(IntPtr hWnd);

to set your window to the foreground, but Microsoft changed it's functionality in Windows ME/2000 onwards (May have been XP?).

There are various work arounds attempts for this issue, you may need to test a few to see which works for you.

http://www.tek-tips.com/faqs.cfm?fid=4262

http://markribau.org/blog/?p=7

I remember reading about a registry entry that can be set to allow SetForegroundWindow to work as desired, but it's a system wide setting.

http://www.delphipages.com/forum/showthread.php?t=198261

You can use SetWindowPos to place you window behind other windows or permanently on top if that helps

http://www.pinvoke.net/default.aspx/user32.SetWindowPos

http://msdn.microsoft.com/en-us/library/ms633545(VS.85).aspx

Answer 2

These links should help:

How to get the z-order in windows?

http://msdn.microsoft.com/en-us/library/ms632599%28VS.85%29.aspx#zorder