[Fix] Correct window event handling and Z-ordering.

Resolves a bug where mouse clicks would "pass through" the top-most
window and incorrectly trigger events on windows visually behind it.

client/src/ui/desktop.cpp

@@ -70,17 +70,32 @@ void Desktop::_set_focused_window(UIWindow* window) {
     return;
   }
 
+  /* Unfocus old window. */
   if(_focused_window) {
     _focused_window->set_focused(false);
   }
 
+  /* Set new focused window. */
   _focused_window = window;
   if(_focused_window) {
     _focused_window->set_focused(true);
+
+    /* Move newly focused window to end of vector so it's rendered on top. */
+    auto it = std::find_if(_windows.begin(), _windows.end(),
+                           [window](const std::unique_ptr<UIWindow>& p) {
+                             return p.get() == window;
+                           });
+    if(it != _windows.end()) {
+      std::rotate(it, it+1, _windows.end());
+    }
   }
 }
 
 void Desktop::handle_event(SDL_Event* event, int screen_width, int screen_height) {
+  /* Let focused window handle all events first. */
+  if(_focused_window) {
+    _focused_window->handle_event(event, screen_width, screen_height, _taskbar->get_height());
+  }
   if(event->type == SDL_EVENT_MOUSE_BUTTON_DOWN) {
     int mouse_x = event->button.x;
     int mouse_y = event->button.y;
@@ -91,15 +106,20 @@ void Desktop::handle_event(SDL_Event* event, int screen_width, int screen_height
       return;
     }
 
-    /* Find the top-most window that was clicked. */
+    /* If click no on focused window, find which window should receive focus. */
+    bool click_on_window = false;
     for(int i = _windows.size()-1; i >= 0; --i) {
       if(_windows[i].get()->is_point_inside(mouse_x, mouse_y)) {
         if(!_windows[i]->is_minimized()) {
           _set_focused_window(_windows[i].get());
         }
+        click_on_window = true;
         break;
       }
     }
+    if(!click_on_window) {
+      _set_focused_window(nullptr);
+    }
   } else if(event->type == SDL_EVENT_MOUSE_BUTTON_UP) {
     if(_taskbar->is_start_button_clicked(event, screen_height)) {
       _launcher_is_open = !_launcher_is_open;
@@ -131,22 +151,14 @@ void Desktop::handle_event(SDL_Event* event, int screen_width, int screen_height
       }
     }
   } else if(event->type == SDL_EVENT_MOUSE_MOTION) {
-    bool on_resize_handle = false;
+    /* Update cursor if hovering over any resize handle. */
-    /* Iterate backwards since top-most windows are at the end. */
     for(int i = _windows.size() - 1; i >= 0; --i) {
       if(_windows[i]->is_mouse_over_resize_handle(event->motion.x, 
                                                   event->motion.y)) {
-        on_resize_handle = true;
+        return CursorManager::set_cursor(CursorType::RESIZE_NWSE);
-        break;
       }
     }
-    CursorManager::set_cursor(on_resize_handle ? CursorType::RESIZE_NWSE
+    CursorManager::set_cursor(CursorType::ARROW);
-                                               : CursorType::ARROW);
-  }
-
-  if(_focused_window) {
-    _focused_window->handle_event(event, screen_width, screen_height,
-                                  _taskbar->get_height());
   }
 }
 
@@ -201,15 +213,12 @@ void Desktop::render(const RenderContext& context) {
   _render_wallpaper(context.ui_renderer);
   context.ui_renderer->flush_text();
 
-  /* Pass 2: Windows (back to front). */
+  /* Pass 2: Windows Render in order, last window is top-most. */
   for(const auto& win : _windows) {
-    if(win.get() != _focused_window && !win->is_minimized()) {
+    if(!win->is_minimized()) {
       win.get()->render(context);
     }
   }
-  if(_focused_window && !_focused_window->is_minimized()) {
-    _focused_window->render(context);
-  }
 
   /* Pass 3: Top-level static UI (taskbar, Launcher, etc.). */
   context.ui_renderer->begin_text();