An application executing on a target platform renders one or more widgets of one or more widget types that are specified by a document including, for each respective widget type from the one or more widget types: render, by a first widget renderer for the respective widget type, the one or more widgets of the respective widget type upon determining that the application includes the first widget renderer for the respective widget type, and render, by a second widget renderer for the respective widget type, the one or more widgets of the respective widget type upon determining that the application does not include the first widget renderer for the respective widget type. The second widget renderer may be different from the first widget renderer.