[FEAT] Add containers and other widgets

[TomJGooding]

Currently textual-dissect only shows the details for the 'core' Textual widgets from the widget gallery. Related widgets are displayed in the inheritance tree and module widgets views, but trying to select those widgets does nothing.

I'm really not sure at the moment the best way to add containers and other widgets in the UI. Should the option list simply include all widgets (maybe with separator lines for different categories)? Or should the widget categories be split by different tab views?

[TomJGooding]

Can this tool be used to drill down on the default CSS for widget sub-classes? For example, Collapsible > Contents has a default CSS padding: 1 0 0 3; (line 163 of _collapsible.py). I can tell that the sub-class exists from looking at the default CSS for Collapsible but the default CSS for the sub-class doesn't "bubble up" to the widget's default CSS. Thoughts?

Originally posted by @DrRichardDaystrom in Textualize/textual#5711 (comment)

[DrRichardDaystrom]

Thanks, @TomJGooding - starred & followed. FWIW, the UI that I was looking for was some sort of Collapsible or Tree for the children of the widget(s). That said, I haven't looked through enough of the widget internals to have a good sense of how deep / complex these child hierarchies are. Regardless, nice project - useful and well built.

[TomJGooding]

Thanks for the feedback. The 'Module Widgets' view was designed to show the child widgets, but I hadn't realised there might be outliers like Collapsible.Contents that are 'hidden' within the widget class itself.

Currently (most) related widgets are displayed in the inheritance tree and module widgets views, but trying to select those widgets does nothing. The problem that I'm struggling with is how to design the UI to incorporate those other widgets.