ivaynberg/select2 — pull request #1984 by jibwa (2013-12-18 21:31:00+00:00)
Title: Fix problem with positioning the dropdown when it is on RHS

In the stable version this line looks like:

dropLeft = offset.left + width - dropWidth;

In line (1193) the variable width is set to dropWidth which means we are always going to end up with

dropLeft = offset.left + X - X
or
dropLeft = offset.left

Which means we are still aligned to the left of the button and this is a bug.

This current solution from @ef9f1dea is just aligning the select2-drop closer to the center which is not what it did before the dropdownAutoWidth.

The line I submitted the select2-drop now aligns to the RHS of the button when that button is on the RHS of the page.