add 'scroll' container property

src/logic/scripting/lua/libs/libgui.cpp

@@ -423,6 +423,13 @@ static int p_get_cursor(UINode* node, lua::State* L) {
     return lua::pushstring(L, to_string(node->getCursor()));
 }
 
+static int p_get_scroll(UINode* node, lua::State* L) {
+    if (auto container = dynamic_cast<Container*>(node)) {
+        return lua::pushnumber(L, container->getContentOffset().y);
+    }
+    return 0;
+}
+
 static int l_gui_getattr(lua::State* L) {
     auto docname = lua::require_string(L, 1);
     auto element = lua::require_string(L, 2);
@@ -469,6 +476,7 @@ static int l_gui_getattr(lua::State* L) {
             {"min", p_get_min},
             {"max", p_get_max},
             {"step", p_get_step},
+            {"scroll", p_get_scroll},
             {"trackWidth", p_get_track_width},
             {"trackColor", p_get_track_color},
             {"textColor", p_get_text_color},
@@ -655,6 +663,13 @@ static void p_set_cursor(UINode* node, lua::State* L, int idx) {
     }
 }
 
+static int p_set_scroll(UINode* node, lua::State* L, int idx) {
+    if (auto container = dynamic_cast<Container*>(node)) {
+        container->setScroll(lua::tointeger(L, idx));
+    }
+    return 0;
+}
+
 static int l_gui_setattr(lua::State* L) {
     auto docname = lua::require_string(L, 1);
     auto element = lua::require_string(L, 2);
@@ -692,6 +707,7 @@ static int l_gui_setattr(lua::State* L) {
             {"min", p_set_min},
             {"max", p_set_max},
             {"step", p_set_step},
+            {"scroll", p_set_scroll},
             {"trackWidth", p_set_track_width},
             {"trackColor", p_set_track_color},
             {"textColor", p_set_text_color},