This works fine in the Ad-Hoc window:
$glob:counter=7;
Output($glob:counter);
$glob:counter=$glob:counter+1;
Output($glob:counter);
++$glob:counter;
Output($glob:counter);
$glob:counter++;
Output($glob:counter);
However, I can't get it to work with a function button:
=$glob:counter=7
=Output($glob:counter)
=$glob:counter=$glob:counter+1
=Output($glob:counter)
=++$glob:counter
=Output($glob:counter)
=$glob:counter++
=Output($glob:counter)