I think that in future versions of Xojo, some sort of shareable inter-platform code of MVC pattern could be implemented, and the User Interface part would be platform specific for the same project. One face for Linux, one face for Windows, one face Android… etc. And a full set of native controls for that platform will be available, not just a small “common core” UI elements. What they do in background could be “essentially” the same (DB, JSON, HTTP, calcs, etc) with some code parts xplat shared, and some parts specific (UI have different events, for example). You should mark parts with a “compile for: All [x], Android [x], iOS [x], Mac[x], Windows[x], …”, but for UI design you should have just one dedicated UI design for each platform. Xojo could also have a virtual platform like “Virtual Display” accepting a common core UI elements (Button, radio, box, …) that is not a “WYSIWYG” but compiles for all those as today AND enable you to create a template enabling you to “clone” a native one. A “clone it for Android”, or “clone it for iOS”, etc where “compatible” controls become native WYSIWYG ones with same names needing just adaptations, enhancements, layout changes, and extra controls.