It would be great to be able to customize what the exact pixel breakpoint is for each device, and also great to be able to add more possibly too
When you enable breakpoints, please then change the defaults of the Desktop, Tablit and Mobile icons in the editor to be those break points.
This is really a necessity. I'm planning to add Builder to an established site, so I need to be able to work with the breakpoints I already have.
Also add the posibility to switch to mobile first responsive breakpoints !