Im trying to implement the solution proposed by user79865 in this thread (which is closed and hence I opened this new question):
function onEdit(e) {
  if (e.range.getW1Notation() == 'X1') {
    if (/^\w+$/.test(e.value)) {        
      eval(e.value)();
      e.range.clear();
    }
  }
}
Unfortunately I get this error:
TypeError: Cannot read property "range" from undefined. (Row 4, File "Makros")
Row 4 is:
  if (e.range.getW1Notation() == 'X1') {
As Im a newbie I have no clue what is going on.
Thanx.
 
    