Hello Ulrich,Customization of the sign in dialog is not currently supported. We are currently working on some additional authentication features that, when released, will enable you to provide a URL to display our custom sign in UI in a web view giving you full control over the sign in experience. This new feature will also include support for IDPs including SAML and OAuth2. As we get further in the development of this feature, I will be able to post the target delivery timeline.Kristy