run the project and enter the size of the canvas - then click either the light blue or light green rectangle to enter a new height or width and the remaining value will be sized appropriately just a little canvas resize calculator for me to use when making art - used to resize images without changing their aspect ratio
I usually open an image in Irfanview, resize it to the old width and height, then adjust either the with or height again to one of the new dimensions with "Preserve aspect ratio" checked to find the other dimension.
