XFC3 Update Applet

I know Tumbleweed zypper dup & Leap zypper up but…

… Is it safe to use update applet for Leap?

It should be safe.
Will it be complete? Maybe. Maybe not.

For all Desktops,
The update applet is configured according to how some person feels it should work, but the only way to be absolutely certain you’re getting everything is to use zypper

zypper up