Problems with Native UI Widgets collection

[jfouse]

I've noticed a few problems that others have reported here as well (e.g. #769, #746, #745) but I've realized they only occur with the Native UI Widgets collection. Notably:

• Stencils don't display text and some formatting when project file is re-opened. Double-clicking reveals the details aren't lost, but in a large project that's obviously prohibitive
• Saving to PDF or PNG loses details/text/etc. Possibly related to the first point?

I've simply started avoiding that collection and haven't had those problems anymore, so I'm pretty sure the issue is specific to that collection and not to Pencil overall.