如何从窗口中删除TOPMOST属性

Question

I have a Windows C++ app that creates two separate windows

I need to be able to make one window topmost temporarily, and then later remove that attribute so that other windows can then overlay it.

I've tried this code:

void setWindowAlwaysOnTop(const std::string& windowTitle, bool onTop) {
    HWND hwnd = FindWindowA(NULL, windowTitle.c_str());
    HWND insertAfter;
    if (onTop) insertAfter = HWND_TOPMOST;  //set the window always-on-top    
    else insertAfter = HWND_BOTTOM; 
    SetWindowPos(hwnd, insertAfter, NULL, NULL, NULL, NULL, SWP_NOMOVE | SWP_NOSIZE);
}

But if I have previously called this code with onTop true it doesn't re-allow other windows to overlay the target window after I call it with onTop false.

I've also tried calling the function from the target window itself rather that from a separate window but it still doesn't work.

As far as I can see at https://docs.microsoft.com/en-us/windows/desktop/api/winuser/nf-winuser-setwindowpos it should work?

Is that correct, or is there another way of achieving this?

Answer 1

The documentation link that you provide in the question indicates that you should pass HWND_NOTOPMOST to hWndInsertAfter . Of this flag it says:

Places the window above all non-topmost windows (that is, behind all topmost windows). This flag has no effect if the window is already a non-topmost window.

Answer 2

Use SetWindowLongPtr . This function will discard your window styles, but u can restore them, like the example below:

SetWindowLongPtr(hWnd, GWL_STYLE, WS_OVERLAPPEDWINDOW); //Discard WS_EX_TOPMOST

To write code that is compatible with both 32-bit and 64-bit versions of Windows, use SetWindowLongPtr. When compiling for 32-bit Windows, SetWindowLongPtr is defined as a call to the SetWindowLong function.

Hope this works.