Changes

[JorjMcKie]

The new test script required significant changes in PyMuPDF's widget handling.

1. Method Page.add_widget(widget): better coverage for creating / extending Radio Button Groups and corresponding RB widgets.
2. Method Page.delete_widget(widget): no changes, turned out to be good enough
3. Function JM_set_widget_properties(annot, Widget): major changes -
   • Full support for updating Radio Button Groups which adhere to the standard, recommended /Kids ⇆ /Parent relationship structure. Other RBG variants are still not supported; these are
     • RBGs defined via JavaScript code (i.e. zero PDF structure)
     • RBGs defined implicitly by the name equality of multiple singleton RB widgets.
     • "No supports" here means that we do not even detect these cases.
   • Full support for updating widgets having a /Parent. In essence, we no longer change field-only properties (like field_name or field_flags) on Widget.update() if the widget has a /Parent.
     • Note that we now always ensure a /Parent (as the actual field) when creating widgets.
     • The /Kids ⇆ /Parent is essential for defining field hierarchies and Widget aliases.