When you start typing in an open Nautilus window by default you'll be going through the folders as you type, a bit like Firefox' quick search.
However, it doesn't always work. I assume the search functionality isn't triggered when the folder view isn't selected, but for many user this is too hard to grasps, or at least confusing.

It would be better if you could trigger the folder view search from everywhere in the window, rather than just when the folder view is selected.

The original reporter provides a very good description of when the 'search folder while typing' doesn't work properly:
"1. Sometimes when opening the Nautilus window the folder view is not selected, so typing into the window does nothing. The tiny search box still pops up as if reassuring the user that it is searching, but nothing appears to be selected.

2. As an example of 1, if the user opens a folder by clicking on a Places bookmark on the left pane then starts typing, it doesn't actually work as the left pane is still highlighted. The only direct visual cue that tells the user that it's not working is the tiny search box that pops up on the left instead of the right, but it's too minor. (The fact that the Places pane doesn't support type-searching compared to Tree and History should also be considered a bug too.)

3. As an example of 1, if the user uses the crumbs buttons in the Location bar, the Go menu, the Bookmarks menu, or selecting tabs, typing into the window doesn't even show the tiny search box.

4. Hitting tab when the user notices problem 2 solves the problem, but requires domain knowledge of the tabbing order of panels in nautilus, and also may require multiple tab presses in problem 3 for example. Pressing the up-down key when problem 3 is noticed also immediately reminds the user where the control is being focused, but requires extra time to discover that and manually target the folder view again, and may also disrupt the current folder view depending on the control selected. (There's also another bug here, where after when the folder view is finally selected by tabbing and the user starts typing, it appears the tiny search box text is not cleared and will just show the junk text from the user's previous search attempts)"

This bug was originally reported by Jerry Chong on Launchpad in Ubuntu at <https://launchpad.net/bugs/404779>.