Firefox and pictures

A while ago I noticed that when I clicked on a picture it started a black screen with a swirly thing that then turned into a picture. I could look at it there or click for the “normal” view. If I looked at it on the black sceen I could hit my “back” button and go back to the previous page. Now I’ve got Firefox when I click the “back” button I go back 2 pages. It’s like Firefox is not treating the black screen as a page. Does anyone understand what I mean and do they know how to fix/deal with it?
Thanks
Don

I figured it out. If I double click I go right by the black screen and it becomes a non-issue
Don

Don - it also takes a bit longer to open (for some of us with dial-up) because Chad increased the file size for files and photos.