diff --git a/src/video/windows/SDL_windowsevents.c b/src/video/windows/SDL_windowsevents.c index c47573e083ab0..81eb3babb673e 100644 --- a/src/video/windows/SDL_windowsevents.c +++ b/src/video/windows/SDL_windowsevents.c @@ -1875,9 +1875,21 @@ LRESULT CALLBACK WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lPara SDL_WindowFlags window_flags = SDL_GetWindowFlags(data->window); if (wParam == TRUE && (window_flags & SDL_WINDOW_BORDERLESS) && !(window_flags & SDL_WINDOW_FULLSCREEN)) { // When borderless, need to tell windows that the size of the non-client area is 0 - if (!(window_flags & SDL_WINDOW_RESIZABLE)) { + NCCALCSIZE_PARAMS *params = (NCCALCSIZE_PARAMS *)lParam; + WINDOWPLACEMENT placement; + if (GetWindowPlacement(hwnd, &placement) && placement.showCmd == SW_MAXIMIZE) { + // Maximized borderless windows should use the full monitor size + HMONITOR hMonitor = MonitorFromWindow(hwnd, MONITOR_DEFAULTTONULL); + if (hMonitor) { + MONITORINFO info; + SDL_zero(info); + info.cbSize = sizeof(info); + if (GetMonitorInfo(hMonitor, &info)) { + params->rgrc[0] = info.rcMonitor; + } + } + } else if (!(window_flags & SDL_WINDOW_RESIZABLE)) { int w, h; - NCCALCSIZE_PARAMS *params = (NCCALCSIZE_PARAMS *)lParam; w = data->window->floating.w; h = data->window->floating.h; params->rgrc[0].right = params->rgrc[0].left + w;