When you select an area of the canvas when using the Sprite Editor, clicking on the Crop icon will resize the canvas down to the selected zone. However, if said selection comes from a pasted image, it instead acts on the entire canvas, just like when no selection has been made. Is it an oversight? I remember it working fine in Construct 2, or rather : I remember it working how I wanted it to! ;)
Either way, I feel it was a slight time save (instead of having to delete what you're pasting your image on beforehand), at least for me and the game I've been trying to make before I upgraded to C3, so I'd like that feature back if that's not too much trouble for what it's ultimately worth.
Thank you for your time and good luck on whatever you're working on! :D