Edwin Pujols authored Dec 10, 2020 and Tomaz Canabrava committed Dec 18, 2020

The terminal display mouse tracking is based on character boxes, i.e.,
unless the mouse moves out of a character box its position hasn't really
changed. So most of the logic in `TerminalDisplay::mouseMoveEvent` can
be skipped/omitted till the pointer crosses box boundaries.

Before my changes applications like Vim/Neovim couldn't do selection via
dragging with the left mouse button (there might be a bug there). I
cursorily checked other features like the color filter and URL
underlining, and they work.