Question

My WPF application has more than one window, I want to attach some of these windows to a window of another process. My problem is that once I attach my window it becomes invisible.

I’m trying this with the following code:

public static bool setParentWindow(IntPtr hWndChild, IntPtr hWndNewParent)
    {
    IntPtr previousParent = SetParent(hWndChild, hWndNewParent);
    return (previousParent == null ? false : true);
}

[DllImport("user32.dll", SetLastError = true)]
private static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent);

setParentWindow(myWindowHwnd, newParentHwnd);

So, the above code successfully attaches the window, but unfortunately makes it invisible.

My reason for doing this is that I’m trying to extend an application by building “Widgets” for it, my widgets will hook in and show the user extra information.

Both windows have the following styles: WS_OVERLAPPEDWINDOW, WS_OVERLAPPED, WS_VISIBLE, WS_CLIPSIBLINGS, WS_CLIPCHILDREN.

Answer 1

I found that I could do this without even using the setParent call. I used HwndSource class as follows:

MyWindow window = new MyWindow();
window.ShowActivated = true;

HwndSourceParameters parameters = new HwndSourceParameters();

parameters.WindowStyle = 0x10000000 | 0x40000000;
parameters.SetPosition(0, 0);
parameters.SetSize((int)window.Width, (int)window.Height);
parameters.ParentWindow = newParent;
parameters.UsesPerPixelOpacity = true;
HwndSource src = new HwndSource(parameters);

src.CompositionTarget.BackgroundColor = Colors.Transparent;
src.RootVisual = (Visual)window.Content;

This is working great now without any problems.