Add a blocker for invalidate_layout().

This will be used by classes that can (partly) handle their own resizes.

src/gui/widgets/window.cpp

@@ -229,6 +229,7 @@ twindow::twindow(CVideo& video,
 	, retval_(NONE)
 	, owner_(0)
 	, need_layout_(true)
+	, invalidate_layout_blocked_(false)
 	, suspend_drawing_(true)
 	, restorer_()
 	, tooltip_()
@@ -667,6 +668,26 @@ void twindow::draw()
 	cursor::undraw(frame_buffer);
 }
 
+twindow::tinvalidate_layout_blocker::tinvalidate_layout_blocker(twindow& window)
+	: window_(window)
+{
+	assert(!window_.invalidate_layout_blocked_);
+	window_.invalidate_layout_blocked_ = true;
+}
+
+twindow::tinvalidate_layout_blocker::~tinvalidate_layout_blocker()
+{
+	assert(window_.invalidate_layout_blocked_);
+	window_.invalidate_layout_blocked_ = false;
+}
+
+void twindow::invalidate_layout()
+{
+	if(!invalidate_layout_blocked_) {
+		need_layout_ = true;
+	}
+}
+
 void twindow::init_linked_size_group(const std::string& id,
 		const bool fixed_width, const bool fixed_height)
 {

src/gui/widgets/window.hpp

@@ -56,6 +56,7 @@ class twindow
 	friend class tdebug_layout_graph;
 	friend twindow* build(CVideo&, const std::string&);
 	friend struct twindow_implementation;
+	friend class tinvalidate_layout_blocker;
 
 public:
 
@@ -181,6 +182,25 @@ public:
 	 */
 	void close() { status_ = REQUEST_CLOSE; }
 
+	/**
+	 * Helper class to block invalidate_layout.
+	 *
+	 * Some widgets can handling certain layout aspects without help. For
+	 * example a listbox can handle hiding and showing rows without help but
+	 * setting the visibility calls invalidate_layout(). When this blocker is
+	 * instanciated the call to invalidate_layout() becomes a nop.
+	 *
+	 * @note The class can't be used recursively.
+	 */
+	class tinvalidate_layout_blocker
+	{
+	public:
+		tinvalidate_layout_blocker(twindow& window);
+		~tinvalidate_layout_blocker();
+	private:
+		twindow& window_;
+	};
+
 	/**
 	 * Updates the size of the window.
 	 *
@@ -188,7 +208,7 @@ public:
 	 * window. To be used after creation and after modification or items which
 	 * can have different sizes eg listboxes.
 	 */
-	void invalidate_layout() { need_layout_ = true; }
+	void invalidate_layout();
 
 	/** Inherited from tevent_handler. */
 	twindow& get_window() { return *this; }
@@ -363,6 +383,9 @@ private:
 	 */
 	bool need_layout_;
 
+	/** Is invalidate layout blocked see tinvalidate_layout_blocker. */
+	bool invalidate_layout_blocked_;
+
 	/** Avoid drawing the window.  */
 	bool suspend_drawing_;