Hello
Due to my big monitor I like to use the smaller size icons from the interface preferences. I decided to look into live booleans yesterday and I couldn’t find anywhere the start from this subtool icon. After searching around I gave up, then it hit me, it might actually be there but I’m not seeing it, and true enough that was the issue, see the picture below
left is the icon on something bigger than button size of 38, right is at 38. As you can see it’s almost invisible if you take into account the color of subtool. Apart from that it seems to be working as expected. I figured I mention this in case somebody else was having a hard time not finding the icon too.