I've already made this request and it has been marked as implemented, but sadly that's not what I asked for.

Now, on the contrary, the problem is even more evident than before!

If I insert the pixels in the dimensions of the canvas by calculating them at 72 dpi, I can use the "print" action, or the dynamic view (things I could not do by inserting the pixels by calculating 300 dpi), but the size of the canvas on the screen is too small and impossible for the user to modify! The new Doyle UI doesn't solve anything, in fact this is how the product looks now:

and this is what happens if I try to zoom:

The "print" action and the dynamic view are absolutely unusable for small products without solving this problem!

I agree if there is a proper 'zoom' function, this editor is simply completed. 

It is not a solution. To zoom I can make the canvas large and keep the product small and the user could use the print action, but the dynamic view is based on the size of the canvas.