Menu bar resizing occurs after overlap of menu option

Current Behaviour:
Resizing the browser window allows overlap with the 'Create Issue' button.
Once reaching the end of the menu item, 'eazyBI Reports' in the attached example, the menu resizes correctly and creates the 'More' menu option.

Expected Behaviour:
Resizing the browser window performs the resize before overlapping the menu item.

Recorded in OnDemand, appears to occur with multiple add-ons enabled with menu bar options.
Reproduced in Chrome and Firefox