It is still a lot of work if you need advanced things then the basic widgets. Thinks where usually you need to extend existing widgets like you want an advanced datagrid/table with sortable/dragable columns, with custom item renders for some columns (like a chart widget for the Trends column).

In this advanced cases you will need to create custom widgets for each platform, hope that all platform have the advanced datagrid widget(if not you will have to create it) etc.

For simple apps your solution works, and you could also make a CLI app too.