Not sure I understand this correctly. 'Click the list and hold the mouse down, your onChange will be called as each item is selected.' Dropdownlists have only one selection. Do you mean that you click the list, hold down the mouse, and drag the mouse pointer across the list? That doesn't trigger onChange on Windows. I don't see any difference in the behaviour of dropdown lists between 2015 and 2014/earlier (on Windows).
On my Mac, 10.9.5, if I click and drag, my onChange is repeatedly called.
I am going to double check this.
My onChange is NOT repeatedly called. The problem, I was deleting and rebuilding the dropdownlist from the onChange routine ( quite a stupid thing to do ).
Sorry about the miss information here.
No worries. Thanks.