We generally avoid hiding UI elements, unless it actually helps understanding context or the UI is expected to do so (e.g. in context menus). Graying out is preferred, since it doesn't confuse users when they are looking for a specific option. The UI stays predictable/familiar, and doesn't change depending on context. Plus, users can still invoke the tooltip, in which we can give more information about why some option isn't available (which isn't supported well enough in Python yet).

I think it's useful to display what the active clip is. Also, the selection of the clip logically should really be above Render Undistorted and Proxy Render Size.

I don't think we need to change anything here.