This is a hand-rolled alternative to the plugin https://github.com/jeffgran/atom-selection-mode.
My two major requests which that plugin doesn't support are:
- Do not deselect when tabbing
- Have an indicator when selection mode is on
My version does both these and is a bit simpler, but also less versatile/general. But it fills my need, and maybe someone else's too.
To get it to work, just paste the bits in the relevant files. Maybe I'll package it into a plugin one day.