In theory, it could be done. But that's as far as I would ever think of. You're adding a bunch of runtime execution dependencies for tiny (if any) benefit. Swing ain't no light widgetset, it's a fully custom drawn one and thus, very heavy. While after having LCL backend for it you can use that custom control, it's limited to that backend, no other widgetset would be able to use it. OTOH, porting the custom control to LCL would be a more beneficial move, especially if you can make it without depending on any specific widgetset functionality and solely rely on existing LCL features, the control would be directly compilable and useable on all existing widgetsets.