The primary issue is that Fuse doesn’t seem to recognise that this refers to the properties, I get this error:
E8001: 'this' declared in MainAppContainer.ux(1) is a member 'MainAppPage' and cannot be accessed from 'OptionsPanel'. To make this work, consider making 'OptionsPanel' an ux:InnerClass of 'MainAppPage'.
The MainAppPage is the parent page of the page that contains the Container.
This looks like a bug. However, it is not generally reproducible, so there must be something else in your project causing the error. Can you please upload a complete test project that reproduces the error?
Yes. this is the default ux:Name of the node with the ux:Class attribute. If you give it an explicit ux:Name, you can no longer use this to refer to that node.
The error message could have been better, but at least not a critical bug then. Thanks for reporting!