Undo is global and not per file

[HB-Stratos]

Replication Steps

• create a project named p1
• create a DF in it and save it as 1
• create a second DF and save it as 2
• modify the DF named 2 in any way (I created an abs with a const of zero)
• switch back to the DF 1
• click undo

--> The undo will now write the contents of the 2 DF into the 1 DF. Undo in an editor should be file specific, not have the ability to overwrite one file with another just by pressing ctrl+z once too often. Thankfully redo can save the day, unless one doesn't notice and switches away. Then one can loose an entire DF.