When you click on this icon the following dialog opens:
Here you can define two values:
If you enter a value greater than zero here, then just this
number of list entries will be memorised, not more. If the list grows
above this value, then the list entries recorded first will be deleted
(FIFO principle: First in, first out!).
The UNDO mechanism takes up memory, in some circumstances quite
a lot. Give a thought to what happens in practice when you delete,
say, a 100 MB TIFF image with a mouse click. So that it may be
restored again with an UNDO later, this mass of data has to be stored
somewhere. At present this will be in RAM memory. To prevent your RAM
memory from overflowing completely at times so that you are unable to
continue working with your document, it is sometimes sensible to limit
the amount of memory available for the UNDO function. (A value of 0
means no limitation).
You can save both values for the next call of the UNDO module in
the Calamus Setup file with the Save system settings entry in
the Options menu.