Hi Tiberiu,

First of all thank you for taking the time to work on this library. It works really well. I use it in one web app I'm working on.

Recently I encountered a small bug when resizing a widget. Here's my use case:
I have a widget with an iframe inside. When I start resizing the widget everything works fine but if I release the mouse over the iframe the code breaks and from then on the widget sticks to the mouse movement and keeps following. The error is shown after clicking again the edges of the widget.

I made a small gif to illustrate the problem:

This error might be related to #214 somehow.

Thanks for your help!