>The edtbox is subclassed from the bsse class editbox.

The nodefault is there to prevent the native behavior of the control. For programmaticchange the behavior is to assign the value to control's .value - so the value wouldn't be assigned.

Just try to assign a value to this editbox's .value from somewhere in the code, and set step on just before that. Put editbox.value in the watch window and, well, watch. Then try with the nodefault commented out. See whether there's a difference.

Without knowing what the rest of the code in programmaticchange does, I figure the purpose of the nodefault is to prevent the programmatic change from happening, or to completely override it.