When I position my cursor over a file name in the Sources folder
of a project, a little box (window is too impressive a word) pops up
with the path displayed with a pale yellow background. Or I should
say sometimes. Sometimes this functionality happens real fast,
but just as often nothing happens.

Is there some "stupid human trick" of something. Because sometimes
the system is very responsive and other times nothing comes up.
What gives?

Also, thought Spotlight did something similar, but I went in just before
I typed this and I couldn't get any path to pop up

WhatMeWorry Wrote:a little box (window is too impressive a word) pops up
with the path displayed with a pale yellow background.

A tooltip, like most people call it

WhatMeWorry Wrote:Sometimes this functionality happens real fast,
but just as often nothing happens.

Well, the tooltip gets shown only when the title of a file is cannot be seen fully, ie if you can read the full name of the file, no tooltip will popup.
Or at least that's what I have noticed.