Resets performance state */

path to plugin manifest

path to plugin files

traverse the layout to locate the nearest character to a display position

API click: on mouse down, move the cursor to the clicked location, and reset the selection

discard the oldest entry in the undo list

find the x/y location of a character, and remember info about the previous row in case we get a move-up event (for page up, we'll have to rescan)

canoncialize the selection so start <= end

find minimum y position if it starts at x1

rects array must be big enough to accommodate all characters in the given ranges