Merge pull request #48156 from madmiraal/fix-46438

Fix `mouse_over` not dropped when mouse leaves window

scene/main/viewport.cpp

@@ -492,20 +492,26 @@ void Viewport::_notification(int p_what) {
 			}
 #endif // _3D_DISABLED
 		} break;
+		case NOTIFICATION_WM_MOUSE_ENTER: {
+			gui.mouse_in_window = true;
+		} break;
 		case NOTIFICATION_WM_MOUSE_EXIT: {
+			gui.mouse_in_window = false;
 			_drop_physics_mouseover();
-
-			// Unlike on loss of focus (NOTIFICATION_WM_WINDOW_FOCUS_OUT), do not
-			// drop the gui mouseover here, as a scrollbar may be dragged while the
-			// mouse is outside the window (without the window having lost focus).
-			// See bug #39634
+			_drop_mouse_over();
+			// When the mouse exits the window, we want to end mouse_over, but
+			// not mouse_focus, because, for example, we want to continue
+			// dragging a scrollbar even if the mouse has left the window.
 		} break;
 		case NOTIFICATION_WM_WINDOW_FOCUS_OUT: {
 			_drop_physics_mouseover();
-
 			if (gui.mouse_focus && !gui.forced_mouse_focus) {
 				_drop_mouse_focus();
 			}
+			// When the window focus changes, we want to end mouse_focus, but
+			// not the mouse_over. Note: The OS will trigger a separate mouse
+			// exit event if the change in focus results in the mouse exiting
+			// the window.
 		} break;
 	}
 }
@@ -1447,8 +1453,6 @@ void Viewport::_gui_input_event(Ref<InputEvent> p_event) {
 	if (mb.is_valid()) {
 		gui.key_event_accepted = false;
 
-		Control *over = nullptr;
-
 		Point2 mpos = mb->get_position();
 		gui.last_mouse_pos = mpos;
 		if (mb->is_pressed()) {
@@ -1594,6 +1598,7 @@ void Viewport::_gui_input_event(Ref<InputEvent> p_event) {
 			// it is different, rather than wait for it to be updated the next time the
 			// mouse is moved, notify the control so that it can e.g. drop the highlight.
 			// This code is duplicated from the mm.is_valid()-case further below.
+			Control *over = nullptr;
 			if (gui.mouse_focus) {
 				over = gui.mouse_focus;
 			} else {
@@ -1601,10 +1606,7 @@ void Viewport::_gui_input_event(Ref<InputEvent> p_event) {
 			}
 
 			if (gui.mouse_focus_mask == MouseButton::NONE && over != gui.mouse_over) {
-				if (gui.mouse_over) {
-					_gui_call_notification(gui.mouse_over, Control::NOTIFICATION_MOUSE_EXIT);
-				}
-
+				_drop_mouse_over();
 				_gui_cancel_tooltip();
 
 				if (over) {
@@ -1625,8 +1627,6 @@ void Viewport::_gui_input_event(Ref<InputEvent> p_event) {
 
 		gui.last_mouse_pos = mpos;
 
-		Control *over = nullptr;
-
 		// Drag & drop.
 		if (!gui.drag_attempted && gui.mouse_focus && (mm->get_button_mask() & MouseButton::MASK_LEFT) != MouseButton::NONE) {
 			gui.drag_accum += mm->get_relative();
@@ -1674,29 +1674,23 @@ void Viewport::_gui_input_event(Ref<InputEvent> p_event) {
 			}
 		}
 
-		// These sections of code are reused in the mb.is_valid() case further up
-		// for the purpose of notifying controls about potential changes in focus
-		// when the mousebutton is released.
+		Control *over = nullptr;
 		if (gui.mouse_focus) {
 			over = gui.mouse_focus;
-		} else {
+		} else if (gui.mouse_in_window) {
 			over = gui_find_control(mpos);
 		}
 
 		if (over != gui.mouse_over) {
-			if (gui.mouse_over) {
-				_gui_call_notification(gui.mouse_over, Control::NOTIFICATION_MOUSE_EXIT);
-			}
-
+			_drop_mouse_over();
 			_gui_cancel_tooltip();
 
 			if (over) {
 				_gui_call_notification(over, Control::NOTIFICATION_MOUSE_ENTER);
+				gui.mouse_over = over;
 			}
 		}
 
-		gui.mouse_over = over;
-
 		DisplayServer::CursorShape ds_cursor_shape = (DisplayServer::CursorShape)Input::get_singleton()->get_default_cursor_shape();
 
 		if (over) {
@@ -2183,6 +2177,13 @@ void Viewport::_gui_accept_event() {
 	}
 }
 
+void Viewport::_drop_mouse_over() {
+	if (gui.mouse_over) {
+		_gui_call_notification(gui.mouse_over, Control::NOTIFICATION_MOUSE_EXIT);
+		gui.mouse_over = nullptr;
+	}
+}
+
 void Viewport::_drop_mouse_focus() {
 	Control *c = gui.mouse_focus;
 	MouseButton mask = gui.mouse_focus_mask;

scene/main/viewport.h

@@ -335,6 +335,7 @@ private:
 		// info used when this is a window
 
 		bool forced_mouse_focus = false; //used for menu buttons
+		bool mouse_in_window = true;
 		bool key_event_accepted = false;
 		Control *mouse_focus = nullptr;
 		Control *last_mouse_focus = nullptr;
@@ -433,6 +434,7 @@ private:
 	void _canvas_layer_add(CanvasLayer *p_canvas_layer);
 	void _canvas_layer_remove(CanvasLayer *p_canvas_layer);
 
+	void _drop_mouse_over();
 	void _drop_mouse_focus();
 	void _drop_physics_mouseover(bool p_paused_only = false);