Dell XPS 18 (1820, Early 2014) - Manual (Page 19)

Using Your Computer │ 19
Finger gestures Allows you to:
Zoom
Place two fingers on the touchscreen
and then move them apart to zoom-in.
Place two fingers on the touchscreen
and then move them apart to zoom-out.
Flick
Move a finger quickly in the desired
direction to flip through content in the
active window like pages in a book.
Flick also works vertically when
navigating content such as images or
songs in a play-list.