[Some of snapping features grayed out]

Thank you for your reply! It would be great if the devs could add  a snap to object nodes feature. That would enable

snapping any node of any object to another object node. Please implement it if possible! :) 

[Some of snapping features grayed out]

Hello, first of all I'd like to thank you for your great software! 

Could you please explain to me why the options shown below in the screenshot are grayed out (not working)? 
Is it a demo version limitation or can they become enabled on certain actions? Thanks in advance.