Disable WPF Window Focus

Question

I have a WPF Window that shows up only when you hold down the tab key via Visibility.Hidden and Visibility.Visible. However, holding the key down shifts the focus from the a

Answer 1

You can prevent a WPF Window from activating on mouse click by adding a custom WndProc and handling WM_MOUSEACTIVATE:

protected override void OnSourceInitialized(EventArgs e)
{
    base.OnSourceInitialized(e);
    var source = PresentationSource.FromVisual(this) as HwndSource;
    source.AddHook(WndProc);
}
private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
    if (msg == WM_MOUSEACTIVATE)
    {
        handled = true;
        return new IntPtr(MA_NOACTIVATE);
    }
    else return IntPtr.Zero;
}
private const int WM_MOUSEACTIVATE = 0x0021;
private const int MA_NOACTIVATE = 0x0003;

References:

• MSDN WM_MOUSEACTIVATE: https://msdn.microsoft.com/en-us/library/windows/desktop/ms645612(v=vs.85).aspx
• How to handle WndProc messages in WPF: How to handle WndProc messages in WPF?
• Notification Window – Preventing the window from ever getting focus: Notification Window - Preventing the window from ever getting focus