Undoing or redoing changes in the global-variables-editor
How to undo the most recent edit action in the global-variables-editor :
In menu Edit, select Undo. Alternative: Press Ctrl+Z.
Repeat the last step as often as you need to reverse editing actions.
How to redo the most recent undone edit action in the global-variables-editor :
In menu Edit, select Redo. Alternative: Press Ctrl+Y.
Repeat the last step as often as you need to re-apply editing actions that have been reversed by Undo