Here is how to add horizontal space within a toolbar docked to the side of a screen

Sometimes I want to add horizontal spaces between toolbar items in a toolbar that is docked to the side of a screen.  Separators do not work for this, because they add just full horizontal lines.  The spacer plug-in works, but it creates a blank area that is square.  So, if you make it too large, it will displace the items below it as well as displacing items toward the right.  You may have to insert several spacers in order to move the items as far to the right as you want.