How to determine if your window is topmost.

// 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);

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

In 1985, I got my first computer Casio MX-10, the cheapest one of MSX home computers. Then I began programming in BASIC and assembly language, and have experienced over ten languages from that time on.
Now, my primary languages are C++ and C#. Working for a small company in my home town in a rural area of Japan.

• My GitHub page: https://github.com/TsudaKageyu
• Official member of WTL Team who maintains the NuGet package.