Minor change to gui

luprex/cpp/viewer.cpp

@@ -14,6 +14,7 @@ int64_t Viewer::get_player_id() {
 }
 
 void Viewer::update_gui(int64_t id, Gui *gui) {
+    gui->clear();
     gui->add_menu_item("north", "north");
     gui->add_menu_item("south", "south");
     gui->add_menu_item("east", "east");

luprex/cpp/viewer.hpp

@@ -34,9 +34,7 @@ public:
 
     // Update the GUI for the specified sprite.
     //
-    // The gui passed in can be either a newly-created empty GUI,
-    // which will be populated, or a GUI object retained from
-    // the previous frame, which will be updated.
+    // The gui passed in will be overwritten.
     //
     void update_gui(int64_t id, Gui *g);
 };