Here is an example of this issue. Steps to reproduce it:

1. Open example using link: http://jsfiddle.net/j53j1mLq/
2. Click on the 'Toggle' button (maybe several times)
3. As you can see, element with height 0 become visible for a short time and it's hidden after that
   I'm waiting for no reaction method call because of element height.

Description: on every button click the 'slideDown' and the 'slideUp' methods are called for the 'box' element in rotation.