add 'edited' read-only textbox property

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

@@ -294,6 +294,13 @@ static int p_get_editable(UINode* node, lua::State* L) {
     return 0;
 }
 
+static int p_get_edited(UINode* node, lua::State* L) {
+    if (auto box = dynamic_cast<TextBox*>(node)) {
+        return lua::pushboolean(L, box->isEdited());
+    }
+    return 0;
+}
+
 static int p_get_line_numbers(UINode* node, lua::State* L) {
     if (auto box = dynamic_cast<TextBox*>(node)) {
         return lua::pushboolean(L, box->isShowLineNumbers());
@@ -451,6 +458,7 @@ static int l_gui_getattr(lua::State* L) {
             {"caret", p_get_caret},
             {"text", p_get_text},
             {"editable", p_get_editable},
+            {"edited", p_get_edited},
             {"lineNumbers", p_get_line_numbers},
             {"lineAt", p_get_line_at},
             {"linePos", p_get_line_pos},