xDM

What does "Refresh application" -button do on a technical level? Load the latest model/UI to tomcat cache? Or/and something else?

Using the Refresh application button that is only available to roles that have Application Design platform privilege (i.e. developers) will reset tomcat cache based on the latest model edition saved.

Its main purpose is to save time for developers, making it possible to see changes in the user application without actually going through the standard deployment process on the data location. The main components that require proper deployment are physical model, integration jobs and security. Other UI components such as form/table views, business views, steppers, UI triggered enrichers/validations, workflows, etc. will be available right after using the Refresh application button.