combo box onChange event

I have a form that needs to be populated with data. The form has a dhtml combo box and has a onChange event. I was able to select the item in the combobox based on the value stored in the database, however the onChange Event is getting fired.

I want the onChange Event to get fired only when the user selects the item not when the form is populated.

onChange event fire each time when new value assigned to the combo, it doesn’t matter is selection produced by user actions, or by API calls
There is no way to change behavior ( you can change code order to attach onChange event only after setting combo value )