UNDOWith the UNDO function you can get back to an earlier stage in your work. However, the program has to know which stage needs to be restored. Therefore you have to wipe the UNDO buffer or cache from time to time. You can do this by pressing Space when the picture is active (Activate - first entry in the main menu). If you do something wrong, you can always get back to this point. Because of this, it is important to press the Spacebar each time you have successfully completed an operation, otherwise you will go back too far. The UNDO function can be activated by pressing F8. Using F7 you can switch between the current and the last saved state - but only if you haven't pressed F8 again.
The MaskThe mask is intended to prevent parts of the picture from being changed. The mask function is well hidden under the entry "Setup" on the main menu over the image window. If you tick "mask" then the current mask will be shown. To define the mask with the drawing tools or the magic wand "edit mask" needs to be ticked. The difference between the 1 and 8 bit mask is that the 1 bit mask will protect areas completely while the 8 bit one has 256 levels. So if you use a 70% mask and paint with a colour it will be lighter at the saved area.
ChoicesUsing the iconbar menu you can alter some choices concerning memory management. You can choose how much RAM and HD space is used by the program.