Hey Max! Sorry for the late reply. Actually - you should know that you are able to open up the Extensions (shown as black balls with XIF) and see the raw source code underneath in those Actions. Good thing OutSystems is based off of standard technology stacks, and lets you bring in any source code, right? :-) Right-click on the Extension (see screenshot) and say Open XYZ extension. It will open up in Integration Studio (that is where you define the interface). Then, assuming you have Visual Studio (even the Community Edition) installed, click on the rightmost icon at top "Edit Source Code .NET" and it will open up the VS project. You could even modify them, recompile them, and re-publish them in Integration Studio to update the reusable visual component in OutSystems! (I'm not a .Net developer myself, but the fact that you can have someone who does know the language create them and make them visually reusable by people like me I think is awesome!). Let me know if that makes sense!