increases, decreases, sets or clears the
The normal level is zero. All current document changes made while the
AtomicUndo level is above zero are treated as a single change by the
Redo commands. If no parameter is given, a level of 0
is set to 1; otherwise the current non-zero level is decremented. If 0 is
given, the level is reset to zero. Parameters of ‘+’ and ‘-’ respectively
increment and decrement the level, which in no case can be negative. If the
level is above zero, the
DoUndo flag in the status bar, which is
normally a lower-case ‘u’, becomes upper case ‘U’.
Two other actions will reset the
AtomicUndo level to zero: invoking the
Undo command, and disabling the undo system with the
command. You cannot set a non-zero
AtomicUndo level unless the undo
system is enabled.
Note: macros that you wish to undo and redo atomically—i.e., as if they
were single commands—should begin with
AtomicUndo + and end with
AtomicUndo - so that they can call and/or be called by other macros.