Windows: fix for client rect resizing larger each time we came from exclusive fullscreen -> windowed on a monitor with HiDPI set. The problem was we were using the monitor DPI rather than the window DPI so AdjustWindowRectExForDpi was giving us an incorrect size which would be too large for the client rect. Closes #8237.

src/video/windows/SDL_windowswindow.c

@@ -190,23 +190,9 @@ static int WIN_AdjustWindowRectWithStyle(SDL_Window *window, DWORD style, BOOL m
         if (WIN_IsPerMonitorV2DPIAware(SDL_GetVideoDevice())) {
             /* With per-monitor v2, the window border/titlebar size depend on the DPI, so we need to call AdjustWindowRectExForDpi instead of
                AdjustWindowRectEx. */
-            UINT unused;
-            RECT screen_rect;
-            HMONITOR mon;
-
-            screen_rect.left = *x;
-            screen_rect.top = *y;
-            screen_rect.right = (LONG)*x + *width;
-            screen_rect.bottom = (LONG)*y + *height;
-
-            mon = MonitorFromRect(&screen_rect, MONITOR_DEFAULTTONEAREST);
-
             if (videodata != NULL) {
-                /* GetDpiForMonitor docs promise to return the same hdpi / vdpi */
-                if (videodata->GetDpiForMonitor(mon, MDT_EFFECTIVE_DPI, &frame_dpi, &unused) != S_OK) {
-                    frame_dpi = 96;
-                }
-
+                SDL_WindowData *data = window->driverdata;
+                frame_dpi = (data && videodata->GetDpiForWindow) ? videodata->GetDpiForWindow(data->hwnd) : 96;
                 if (videodata->AdjustWindowRectExForDpi(&rect, style, menu, 0, frame_dpi) == 0) {
                     return WIN_SetError("AdjustWindowRectExForDpi()");
                 }