reverse any action made on your Mandala. Simply press CTRL-Z or go to Main Menu / Edit / Undo.
You can undo several actions at a time, just select more than one from the list.
Every Mandala has a memory limit that controlled by these settings: Main Menu / Mandala / Preferences / Undo tab
Every Mandala can allocate the Maximum memory for undo value so take care if you have more than one Mandala opened.
If you have 500 MB of memory you can set it to 100 MB, if you have 1GB of Memory you can set it to 200 MB.
This setting is important if you work on high resolution Mandalas. As a bigger Mandala requies more memory you should increase this value.
- Maximum undo items per Mandala controls the maximum number of the undo actions. Generally you can set this to higher than 100 eg. 500.