My IT department just upgraded me to Snag It 18. When I resized the canvas in the previous version, the canvas would resize dynamically while the Resize Canvas dialog box was open. As such, I could see the results as I adjusted the width and height.
With version 18, I have to click the OK button in the Resize Canvas dialog box in order to see the results. If I need to adjust the width and height, I need to go back into the Resize Canvas dialog box. That's more mouse clicks than in the previous version. That does not make for an improved user experience.