This is a pre-beta performance preview and has known issues with some components.I've been playing with 4.1-pr1 for a few hours now and I've run into a number of issues. It's difficult to judge what counts as a 'known issue' and what counts as a 'migration problem' without some guidance as to the known issues. Or would you prefer that we just report everything we find and leave filtering out of the known issues to you?We are expecting some applications to need changes to migrate to 4.1 using this preview–especially if you have written custom layouts and components. This is because we altered some of the low-level architecture of the layout engine, which can have some impact on some more advanced usage of the framework. We will work with you to resolve these issues, and have created a dedicated forum to collect any migration problems you encounter so that we can improve that experience as we approach 4.1 beta.