Make sure we don't clip the cursor while clicking on the window title bar

src/video/windows/SDL_windowsevents.c

@@ -570,6 +570,20 @@ WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
         break;
 #endif /* WM_INPUTLANGCHANGE */
 
+    case WM_NCLBUTTONDOWN:
+        {
+            data->in_title_click = SDL_TRUE;
+            WIN_UpdateClipCursor(data->window);
+        }
+        break;
+
+    case WM_NCMOUSELEAVE:
+        {
+            data->in_title_click = SDL_FALSE;
+            WIN_UpdateClipCursor(data->window);
+        }
+        break;
+
     case WM_ENTERSIZEMOVE:
     case WM_ENTERMENULOOP:
         {

src/video/windows/SDL_windowswindow.c

@@ -746,7 +746,7 @@ WIN_UpdateClipCursor(SDL_Window *window)
     SDL_Mouse *mouse = SDL_GetMouse();
 
     /* Don't clip the cursor while we're in the modal resize or move loop */
-    if (data->in_modal_loop) {
+    if (data->in_title_click || data->in_modal_loop) {
         ClipCursor(NULL);
         return;
     }

src/video/windows/SDL_windowswindow.h

@@ -38,6 +38,7 @@ typedef struct
     SDL_bool created;
     WPARAM mouse_button_flags;
     BOOL expected_resize;
+    SDL_bool in_title_click;
     SDL_bool in_modal_loop;
     struct SDL_VideoData *videodata;
 #if SDL_VIDEO_OPENGL_EGL