Rated 5 out of 5 stars

nice utility , one suggestion :
- in firefox on mac once the picniche options are selected there's no way to close the window ( only force quit worksin that case )

This review is for a previous version of the add-on (1.1.10). 

Edited November 4th: This should now be fixed in the latest release (1.1.15) (though you 'might' still need to use the escape key to close the shelf (the preferences are saved as and when you change them in firefox for mac), my own mac shows a close button, but a friend's doesn't. I presume it might be caused by a system-wide setting for dialog windows (I'm not much of a mac person so don't know for sure)