Issue with SetForegroundWindow in .NET

Question

I\'m using SetForegroundWindow API in .NET using PInvoke.

When I use the API while debugging in Visual Studio its works perfectly. But it doesn\'t work always when

Answer 1

The trick is to 'fool' windows (not trying to talk in pleonasms) and attach the input to the new thread to which the window-to-focus belongs, I took most of this from the pinvoke website but added a test to restore minimized windows:

private const uint WS_MINIMIZE = 0x20000000;

private const uint SW_SHOW     = 0x05;
private const uint SW_MINIMIZE = 0x06;
private const uint SW_RESTORE  = 0x09;

public static void FocusWindow(IntPtr focusOnWindowHandle)
{
    int style = GetWindowLong(focusOnWindowHandle, GWL_STYLE);

    // Minimize and restore to be able to make it active.
    if ((style & WS_MINIMIZE) == WS_MINIMIZE)
    {
        ShowWindow(focusOnWindowHandle, SW_RESTORE);
    }

    uint currentlyFocusedWindowProcessId = GetWindowThreadProcessId(GetForegroundWindow(), IntPtr.Zero);
    uint appThread = GetCurrentThreadId();

    if (currentlyFocusedWindowProcessId != appThread)
    {
        AttachThreadInput(currentlyFocusedWindowProcessId, appThread, true);
        BringWindowToTop(focusOnWindowHandle);
        ShowWindow(focusOnWindowHandle, SW_SHOW);
        AttachThreadInput(currentlyFocusedWindowProcessId, appThread, false);
    }

    else
    {
        BringWindowToTop(focusOnWindowHandle);
        ShowWindow(focusOnWindowHandle, SW_SHOW);
    }
}