The first photographs printed out in daylight and never stopped: every look darkened them a little more, until the picture went under its own shadow. Fixing washes out the silver light has not reached yet. After that, nothing changes the print.
This sheet is Daguerre's boulevard on salted paper, and the room is lit. Your pointer is a lamp. Looking at the picture is what prints it, and what will spoil it.
move over the paper to light it · press and hold for a brighter lamp · fix it when it looks right (or press f) · on a phone, drag a finger
unfixed · 0 s of lamp · latent, almost nothing has come up yet