Yes, and with Edit (T) enabled. The ZBrush UI is context-sensitve and UI items will only show when applicable.
That is in “Render > Render Booleans” subpalette. If you move your cursor over a button and hold down Ctrl, it will give you a description of the button and the button path. This works for most but not all buttons and sliders.
The minimum screen resolution for ZBrush is 1280 x 1024, but you can still slide all of the shelves and then move the buttons to a convenient place.
Hold down Ctrl and move your cursor beside one of the icons or buttons on the right shelf, you will get an up/down arrow. When you get that, you can slide the shelf up or down. It’s kind of fiddly because the area to get the up/down arrow is small. If you temporarily remove an icon or button from the right shelf, you can use that space to get the up/down arrow much easier. This works the same for all the shelves. Top, bottom left and right. Except, for the top and bottom shelves, it will be a left/right arrow.