LibGUI: Move the editing widget along with the content when scrolling.

LibGUI/GAbstractView.cpp

@@ -41,3 +41,15 @@ void GAbstractView::did_update_model()
 void GAbstractView::did_update_selection()
 {
 }
+
+void GAbstractView::did_scroll()
+{
+    update_edit_widget_position();
+}
+
+void GAbstractView::update_edit_widget_position()
+{
+    if (!m_edit_widget)
+        return;
+    m_edit_widget->set_relative_rect(m_edit_widget_content_rect.translated(-horizontal_scrollbar().value(), -vertical_scrollbar().value()));
+}

LibGUI/GAbstractView.h

@@ -29,10 +29,13 @@ public:
 
 protected:
     virtual void model_notification(const GModelNotification&);
+    virtual void did_scroll() override;
+    void update_edit_widget_position();
 
     bool m_editable { false };
     GModelIndex m_edit_index;
     GTextBox* m_edit_widget { nullptr };
+    Rect m_edit_widget_content_rect;
 
 private:
     RetainPtr<GModel> m_model;

LibGUI/GScrollableWidget.cpp

@@ -7,6 +7,7 @@ GScrollableWidget::GScrollableWidget(GWidget* parent)
     m_vertical_scrollbar = new GScrollBar(Orientation::Vertical, this);
     m_vertical_scrollbar->set_step(4);
     m_vertical_scrollbar->on_change = [this] (int) {
+        did_scroll();
         update();
     };
 
@@ -14,6 +15,7 @@ GScrollableWidget::GScrollableWidget(GWidget* parent)
     m_horizontal_scrollbar->set_step(4);
     m_horizontal_scrollbar->set_big_step(30);
     m_horizontal_scrollbar->on_change = [this] (int) {
+        did_scroll();
         update();
     };
 

LibGUI/GScrollableWidget.h

@@ -39,6 +39,7 @@ public:
 protected:
     explicit GScrollableWidget(GWidget* parent);
     virtual void resize_event(GResizeEvent&) override;
+    virtual void did_scroll() { }
     void set_content_size(const Size&);
     void set_size_occupied_by_fixed_elements(const Size&);
 

LibGUI/GTableView.cpp

@@ -339,8 +339,10 @@ void GTableView::begin_editing(const GModelIndex& index)
         delete m_edit_widget;
     m_edit_index = index;
     m_edit_widget = new GTextBox(this);
+    m_edit_widget->move_to_back();
     m_edit_widget->set_text(model()->data(index, GModel::Role::Display).to_string());
-    m_edit_widget->set_relative_rect(cell_content_rect(index));
+    m_edit_widget_content_rect = cell_content_rect(index);
+    update_edit_widget_position();
     m_edit_widget->set_focus(true);
     m_edit_widget->on_return_pressed = [this] {
         ASSERT(model());