Currently, the size of the designs can have FACTOR (relative to image original size) and ABSOLUTE values in pixels, but not in %, relative to the designer canvas.
Would be very useful to be able to set the designs size to appear RELATIVE to canvas size in percents.
For example, setting width / height 100% will show the design 100% of the canvas.
Actually, I'm wondering how such basic feature is not the part of core plugin yet :)
If you want to fit designs to 100% of the canvas, you can enable the option "Fit Images into canvas" under the Advanced section.
100% was just one example, that may be good only for certain categories that have backgrounds that needed to be displayed 100%, but if I set the option that you have suggested, all the designs will fit 100% without other custom sizes.
But what if other categories have designs that needed to appear 20 / 30 / 40 / 60 / 80% relatively to the CANVAS?
I'm talking about adding a setting to the design category options, where you have design resizing parameters 1) factor (relative to original image size) 2) pixels, but not % relatively to CANVAS. It is a third very useful resizing parameter that will add real control of customizing and appearance of the designs in the canvas.