How can I prevent a window from being deactivated?

Question

Is there any way to prevent a window from being deactivated? The window is in a different process then mine.

This is for Windows.

Answer 1

Doing this can be dangerous, but the solution is to handle the WM_ACTIVATE message and check if the wParam is WA_INACTIVE. This means the window has been deactivated. When this happens, you can just reactivate it.

In order to do this for another process's window, you will need to install a message hook with SetWindowsHookEx.

However, it is possible that another application could do the same thing, putting each other in an endless loop of activation/deactivation.

This is also something that should never be done by software that is meant to run on a personal computer.

Answer 2

You can trap the WM_ACTIVATEAPP like this:

protected override void WndProc(ref Message m) {
  // Trap WM_ACTIVATEAPP
  if ((m.Msg == 0x1c) && (m.WParam == IntPtr.Zero))
  {
     // If WM_ACTIVATEAPP and WParam is deactivated, return
     return;
  }
  base.WndProc(ref m);
}