Improve UX for random seed

[sudara]

Got a bit confused by this UI today.

No random seed: still displays the seed number (you have to read the code to know "0x0/0" translates to "no random seed", which feels ambiguous once you start working with seeds and then want to remove)

With random seed: doesn't have a checkmark, so I've done things like try to select it again, unsure if it's actually using it.

Improvement would be:

• More clearly showing no random seed being used
• Adding checkmark when random seed is being used
• Instructing people on how to remove the random seed once its set, for example saying "Set to 0 to use a different seed on each run":