(i made this picture in the Scratch forums because i don't know how to make dropdowns in custom blocks)
Wouldn't it be cool to be able to detect left clicking, right clicking, and middle button clicking?
I'm not sure why you would need middle button clicking, but it wouldn't make sense to only have right and left click and not middle click.
So, because right clicking in the editor actually serves a purpose, it should only detect right clicking in the project page or in fullscreen.
It would be useful for me in my missile command program as it has 3 missile bases
But it would make development/debugging of all but a trivial program quite difficult because of all the swapping back and forth between editor and full-screen
But full marks for thinking outside of the box
We're not going to introduce features that work differently in edit mode from in presentation mode; that would confuse users, make debugging hard, and lead to a lot of spurious bug reports. So you're definitely not going to get a right-button block.