GUI: Make container widget a bit more container like.

Now it is possible to add sub widgets to a ContainerWidget and allow for these
to get events too.

gui/widget.cpp

@@ -711,6 +711,26 @@ ContainerWidget::ContainerWidget(GuiObject *boss, const Common::String &name) :
 	_type = kContainerWidget;
 }
 
+ContainerWidget::~ContainerWidget() {
+	// We also remove the widget from the boss to avoid segfaults, when the
+	// deleted widget is an active widget in the boss.
+	for (Widget *w = _firstWidget; w; w = w->next()) {
+		_boss->removeWidget(w);
+	}
+}
+
+Widget *ContainerWidget::findWidget(int x, int y) {
+	return findWidgetInChain(_firstWidget, x, y);
+}
+
+void ContainerWidget::removeWidget(Widget *widget) {
+	// We also remove the widget from the boss to avoid a reference to a
+	// widget not in the widget chain anymore.
+	_boss->removeWidget(widget);
+
+	Widget::removeWidget(widget);
+}
+
 void ContainerWidget::drawWidget() {
 	g_gui.theme()->drawWidgetBackground(Common::Rect(_x, _y, _x + _w, _y + _h), 0, ThemeEngine::kWidgetBackgroundBorder);
 }

gui/widget.h

@@ -368,7 +368,10 @@ class ContainerWidget : public Widget {
 public:
 	ContainerWidget(GuiObject *boss, int x, int y, int w, int h);
 	ContainerWidget(GuiObject *boss, const Common::String &name);
+	~ContainerWidget();
 
+	virtual Widget *findWidget(int x, int y);
+	virtual void removeWidget(Widget *widget);
 protected:
 	void drawWidget();
 };