The Type tool heard of Undo and Redo only when they ran as top-level
commands. As steps of command.batch, they left the caret where it was,
and the tool took the batch for an outside edit. Session::execute now
tells the active tool about each nested edit.undo and edit.redo.
command.batch also tells the tool when it begins, ends or rolls back.
The Type tool keeps its caret and its edit records at the start of each
batch and puts them back when a failed batch rolls the documents back.
While the Type tool edits type, Edit > Undo and Redo (the menu, the
keyboard, the History panel and MCP all run edit.undo and edit.redo)
left the caret at its byte offset, clamped to the text. Typing "abc"
before "XYZ" and pressing Undo left the caret after "XYZ".
The engine now tells the active tool about edit.undo and edit.redo
before it finishes the command. The Type tool keeps the edited text and
a list of the steps that changed it, and puts the caret, with nothing
selected, at the end of the span the step changed: where typed text
began after its Undo, after restored text after the Undo of a deletion,
and after retyped text after Redo. For the steps the tool made, it keeps
where the span ended, so text that repeats the characters next to it
puts the caret at the right end. A step that changes no characters,
such as a formatting change, leaves the caret and the selection as they
are. Typed lists keep their caret positions.
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