Added experimental listbox grow support.

This allows a listbox to grow, but keep the unused area blank instead of
trying to allocate it for it's content. The feature had minimal testing,
but ran into a problem that the stacked widget doesn't let the room
grow. This needs to be fixed before testing further.

data/gui/default/window/lobby_main.cfg

@@ -632,7 +632,7 @@
 										grow_factor = 1
 										[column]
 											horizontal_grow = "true"
-											vertical_alignment = "top"
+											vertical_grow = "true"
 											{GUI_FORCE_WIDGET_MINIMUM_SIZE 0 "((screen_height * 30) / 100)"  (
 												{GAMELISTBOX}
 											)}

src/gui/widgets/listbox.cpp

@@ -419,5 +419,15 @@ void tlistbox::finalize(
 
 }
 
+void tlistbox::set_content_size(const tpoint& origin, const tpoint& size)
+{
+	/** @todo This function needs more testing. */
+	assert(content_grid());
+
+	const int best_height = content_grid()->get_best_size().y;
+	const tpoint s(size.x, size.y < best_height ? size.y : best_height);
+	content_grid()->set_size(origin, s);
+}
+
 } // namespace gui2
 

src/gui/widgets/listbox.hpp

@@ -287,6 +287,9 @@ private:
 	 */
 	bool linked_widgets_disabled_;
 
+	/** Inherited from tscrollbar_container. */
+	virtual void set_content_size(const tpoint& origin, const tpoint& size);
+
 	/** Inherited from tcontrol. */
 	const std::string& get_control_type() const
 		{ static const std::string type = "listbox"; return type; }

src/gui/widgets/scrollbar_container.cpp

@@ -310,7 +310,7 @@ void tscrollbar_container::
 			std::max(best_size.x, content_size.x),
 			std::max(best_size.y, content_size.y));
 
-	content_grid_->set_size(content_origin, content_grid_size);
+	set_content_size(content_origin, content_grid_size);
 
 	// Set vertical scrollbar
 	set_scrollbar_mode(vertical_scrollbar_grid_, vertical_scrollbar_,
@@ -568,6 +568,12 @@ void tscrollbar_container::child_populate_dirty_list(twindow& caller,
 	content_grid_->populate_dirty_list(caller, child_call_stack);
 }
 
+void tscrollbar_container::set_content_size(
+		const tpoint& origin, const tpoint& size)
+{
+	content_grid_->set_size(origin, size);
+}
+
 void tscrollbar_container::show_content_rect(const SDL_Rect& rect)
 {
 	assert(content_);

src/gui/widgets/scrollbar_container.hpp

@@ -392,6 +392,17 @@ private:
 	void child_populate_dirty_list(twindow& caller,
 		const std::vector<twidget*>& call_stack);
 
+	/**
+	 * Sets the size of the content grid.
+	 *
+	 * This function normally just updates the content grid but can be
+	 * overridden by a subclass.
+	 *
+	 * @param origin              The origin for the content.
+	 * @param size                The size of the content.
+	 */
+	virtual void set_content_size(const tpoint& origin, const tpoint& size);
+
 	/** Helper function which needs to be called after the scollbar moved. */
 	void scrollbar_moved();