Implement a "rich text context/scope"

[SamRodri]

That is a way for texts to know their sibling texts in the same Wrap panel. This context should enable multiple features:

• White space collapse across texts.
• Justify in rich text.
• Selection across texts (copy concatenates).
• Edit across multiple texts.

The text context takes over commands like undo, clipboard. Maybe can be generalized as each text is its own scope by default, but a contextual scope overrides it.