Use Firefox on Ubuntu with touchscreen

By default Firefox had pretty bad touch support for me. E.g. no scrolling or zooming. But this was easy to change. Go to about:conifg in Firefox and set dom.w3c_touch_events.enabled=1. Then test this by running the following:

env MOZ_USE_XINPUT2=1 firefox

Change this as the default when starting Firefox.

sudo sed -i "s|Exec=|Exec=env MOZ_USE_XINPUT2=1 |g" /usr/share/applications/firefox.desktop