RFR: JDK-8290010: IGV: Fix UndoRedo Action [v2]

[Tobias Holenstein]

On Mon, 24 Oct 2022 10:40:55 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

> In general, it seems that when going backwards (undo) multiple steps, going forwards (redo) does not work anymore after one step forward.

Hi @TobiHartmann 
Thanks for trying it out and reporting. It should be fixed now!

The problem was that during `undo()`/ `redo()` we recorded new states to the history with `addUndo()`
The fix is to disable `addUndo()` while performing `undo()`/ `redo()`

When we now call `redo()` should we have now the following behavior:
1. (1)->(2)->**(3)**   →  _undo (2), redo (-)_
- we select _undo (2)_
2. (1)->**(2)**   →   _undo (1), redo (3)_
- if we now redo (3) we end up in 1.
- if we change the selection or the graph we override state (3) in the history and end up in 3.
3. (1)->(2)->**(4)** →  _undo (2), redo (-)_
- we select _undo (2)_
4. (1)->**(2)**   →   _undo (1), redo (4)_
- state (3) cannot be reached anymore because we rewrote the history

(Nr) represents a saved state, -> is a recording with `addUndo()`, right of  → are the possible actions at the **bold** state

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PR: https://git.openjdk.org/jdk/pull/10813