What features would you like to see in Pixelmator Pro?
Hey Kobold! Double-click on a tool icon is dedicated to opening the list of tools in case a tool is grouped, so this wouldn't really be possible. However, since Hide/Show Tool Options is available from the View menu at the top, you can assign a custom keyboard shortcut to it and make it super easy to turn on or off. You can learn how to create shortcuts for your Mac apps here.