What is the grey check mark in gutter?

Hello ethan,

That's an unnumbered bookmark. You also have actions to navigate to next/previous
bookmarks or to see a list of them (Shift + F11, AFAIR).

HTH,
Andrei

e> When I put the insertion point in a line of code and press F11 a grey
e> check mark appears in the left gutter (the same area where the
e> breakpoint red dots are displayed) by the line. Also a black bar
e> appear in the right gutter.
e>
e> What's up with that?
e>
e> Thanks,
e>
e> E
e>