DTL Editor: Undo Action Collapses All Expanded Source/Target Field Trees

When working on a Data Transformation (DTL) with a complex HL7 message structure, I usually need to expand several levels of the source and target field trees (repeating groups, segments, components) to build and review my mappings comfortably.

The problem is that every time I use the Undo button after making a change, the entire source and target trees collapse back to their default state, losing all the expanded nodes I had open. This means I have to manually re-expand everything from scratch just to get back to the view I was working with, which significantly slows down development, especially in DTLs with many nested groups and long field paths.

Suggested improvement:

• When undoing an action, the editor should preserve the current expand/collapse state of the source and target field trees, instead of resetting them.

• It would also be very helpful to have a visible history of undone/redone actions (similar to an undo/redo stack list), so developers can see what was changed and quickly jump to a specific point in the edit history instead of clicking Undo repeatedly and guessing.