Win32: Bring a window to top

try this，it is said coming from M$

    HWND hCurWnd = ::GetForegroundWindow();
    DWORD dwMyID = ::GetCurrentThreadId();
    DWORD dwCurID = ::GetWindowThreadProcessId(hCurWnd, NULL);
    ::AttachThreadInput(dwCurID, dwMyID, TRUE);
    ::SetWindowPos(m_hWnd, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE);
    ::SetWindowPos(m_hWnd, HWND_NOTOPMOST, 0, 0, 0, 0, SWP_SHOWWINDOW | SWP_NOSIZE | SWP_NOMOVE);
    ::SetForegroundWindow(m_hWnd);
    ::SetFocus(m_hWnd);
    ::SetActiveWindow(m_hWnd);
    ::AttachThreadInput(dwCurID, dwMyID, FALSE);

In order to bring a window to top, you should get your window handle,thread handle, the windows thread handle who is in foreground

then we attach our thread to foreground window thread and get input by AttachThreadInput, then we set our window z order to topmost and then restore its z order to normal, call SetForegroundWindow,SetFocus,SetActiveWindow to make sure our window is brought to top and is active and have focus

then deattach the input queue from the old foreground window thread, make our thread the only one who capture the input events

So why should We call AttachThreadInput, it is because

SetFocus sets the keyboard focus to the specified window. The window must be attached to the calling thread's message queue.

What does AttachThreadInput do?

The AttachThreadInput function can be used to allow a set of threads to share the same input state. By sharing input state, the threads share their concept of the active window. By doing this, one thread can always activate another thread's window. This function is also useful for sharing focus state, mouse capture state, keyboard state, and window Z-order state among windows created by different threads whose input state is shared.

We use SetWindowPos to bring the windows to topmost and show the window if the window is hidding by using SWP_HIDEWINDOW

SetWindowPos function changes the size, position, and Z order of a child, pop-up, or top-level window. These windows are ordered according to their appearance on the screen. The topmost window receives the highest rank and is the first window in the Z order

If your problem is your window is also minimized , you should add one line code to the end

ShowWindow(m_hWnd, SW_RESTORE);

Both work great:

::SetForegroundWindow(wnd)

::SetWindowPos(m_hWnd,       // handle to window
            HWND_TOPMOST,  // placement-order handle
            0,     // horizontal position
            0,      // vertical position
            0,  // width
            0, // height
            SWP_SHOWWINDOW|SWP_NOSIZE|SWP_NOMOVE// window-positioning options
            );

But remember that the last one sets the window always on top.

After many tries and errors.I found following solution to this problem:

SendMessage(hwnd, WM_SYSCOMMAND, SC_RESTORE, 0); // restore the minimize window
SetForegroundWindow(hwnd); 
SetActiveWindow(hwnd); 
SetWindowPos(hwnd, HWND_TOP, 0, 0, 0, 0, SWP_SHOWWINDOW | SWP_NOMOVE  | SWP_NOSIZE);
//redraw to prevent the window blank.
RedrawWindow(hwnd, NULL, 0, RDW_FRAME | RDW_INVALIDATE | RDW_ALLCHILDREN );

The hwnd is your windows HWND . Please do not just copy and paste. You also need use GetLastError to check api error after every api call.

I have confirm following result on my win7:

Can restore minimize window and no error return.
If the window already top, the window title will blink and no error return.
If the window has closed, it will return the error "0x578 Invalid window handle."
It can bring the window to the top on all not top-most window and no error return.(For example it will behind the top-most taskmanager)
It do not make the window top-most. The user can make other window on top of it.

Win32: Bring a window to top

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