This is not a bug that I expect to get fixed in Elements (or anywhere else), but something I just wanted to see documented and this was the best place I could think of.

When using a range element with an #ajax callback, Webkit based browsers (tested Safari and Chrome), will not release the range knob if the mouseup event occurs before the 'disabled' attribute is removed by ajax. This means that after mouseup you still move the range knob while not pressing any mouse buttons (untill you click anywhere else, then it gets released).

changing
$(this.element).addClass('progress-disabled').attr('disabled', true);
on line 359 in ajax.inc (in core) to
$(this.element).addClass('progress-disabled');
solves the issue

I managed the same thing by adding a new Drupal.ajax.prototype.beforeSend prototype in a new javascript file only included when my range fields are shown.

It's a bug in Webkit (might not be seen as a bug though, there is some discussion about whether disabled elements should handle any events), that expresses itself because of a line of code in Drupal core that is only relevent when using the Elements module. So, like I said, just wanted to document it, so people can find something when looking for bugs with ajax and range elements.

Lendude