Use RAII instead of lock->unlock directly.

src/display.cpp

@@ -2720,10 +2720,9 @@ void display::draw(bool update,bool force) {
 	}
 
 	if (dirty_) {
+		flip_locker flip_lock(screen_);
 		dirty_ = false;
-		screen_.lock_flips(true);
 		redraw_everything();
-		screen_.lock_flips(false);
 		return;
 	}
 

src/events.cpp

@@ -471,7 +471,7 @@ void pump()
 			}
 			case DRAW_ALL_EVENT:
 			{
-				CVideo::get_singleton().lock_flips(true);
+				flip_locker flip_lock(CVideo::get_singleton());
 				/* iterate backwards as the most recent things will be at the top */
 				for( std::deque<context>::iterator i = event_contexts.begin() ; i != event_contexts.end(); ++i) {
 					const std::vector<sdl_handler*>& event_handlers = (*i).handlers;
@@ -479,8 +479,6 @@ void pump()
 						(*i1)->handle_event(event);
 					}
 				}
-				CVideo::get_singleton().lock_flips(false);
-				//CVideo::get_singleton().flip();
 				continue; //do not do further handling here
 			}
 

src/video.hpp

@@ -272,6 +272,21 @@ private:
 	bool unlock;
 };
 
+class flip_locker
+{
+public:
+	flip_locker(CVideo &video) : video_(video) {
+		video_.lock_flips(true);
+	}
+	~flip_locker() {
+		video_.lock_flips(false);
+	}
+
+private:
+	CVideo& video_;
+};
+
+
 namespace video2 {
 class draw_layering: public events::sdl_handler {
 protected: