Using a select tool comes with four options for adjusting your selection: replace with, add to, subtract from, & intersect with current selection. The last 3 can be activated by holding down Shift, Ctrl, & Ctrl + Shift, respectively, or you can click their icon to make them active without holding a key down. Is there a hotkey that can do the same thing as clicking the icons? I looked in the hotkeys menu & found some possibilities, but after assigning keys to them & trying them out, I found they did not work as intended.