Add ui::container_impl::clear

libs/ui/include/psemek/ui/container_impl.hpp

@@ -28,6 +28,8 @@ namespace psemek::ui
 		std::shared_ptr<element> remove(element * c);
 		std::shared_ptr<element> remove(std::size_t index);
 
+		void clear();
+
 	protected:
 		element * parent_;
 		std::vector<std::shared_ptr<element>> children_;

libs/ui/source/container_impl.cpp

@@ -82,4 +82,13 @@ namespace psemek::ui
 		return c;
 	}
 
+	void container_impl::clear()
+	{
+		for (std::size_t i = 0; i < children_.size(); ++i)
+			remove(i);
+
+		children_.clear();
+		children_range_.clear();
+	}
+
 }