How to determine if your window is topmost.

It's a well known tip how to make your window topmost or "Always on Top".

// Make topmost
::SetWindowPos(hwnd, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE);

// Revert back
::SetWindowPos(hwnd, HWND_NOTOPMOST, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE);

Well, how can you determine if your window is topmost? You can do it like this:

if (::GetWindowLong(hwnd, GWL_EXSTYLE) & WS_EX_TOPMOST)
    ... // The window is topmost.
else
    ... // The window is not topmost.

This is because SetWindowsPos()gives WS_EX_TOPMOST extended style to your window when it makes the window topmost.