Undo button cancels any action made after defining an output variable

[Victorien-V]

When we define an output variable, Undo button starts cancelling any action made starting from that point, instead of cancelling only one action at a time.

What steps will reproduce the problem?

1. Launch Unitex with any language
2. Create a new graph with FSGraph > New
3. Create an empty box using the "Create new box" button
4. Link boxes from starting node to your box and from your box to end node using "Normal editing mode"
5. Select your new box
6. Surround it with an output variable by clicking the "Surround box selection with an output variable" button, choose any name for your variable
7. Create a new empty box using the "Create new box" button
8. Click the "Undo" button

What is the expected output?

Undo button should cancel only the last action (Create new box).

What do you see instead?

Undo button cancels all the actions made after clicking "Surround box selection with an output variable" button, including "Surround box selection with an output variable" itself.

More info

• Unitex/GramLab IDE version: 3.2.56-alpha
• UnitexToolLogger version: 3.2.57-alpha