This has annoyed me for nearly two years now:

The little 'up' and 'down' arrows next to the find box have the same [next to invisible] grey colour whether there are any results to be found in that direction or not. You click one, and then you wait, and then you wonder if the lack of response is because there isn't anything to be found, or if it is because it hasn't finished searching yet, and then you wait some more, and then you click your way back to where you started and go through the same thing in the other direction.
Usually, the reason nothing happens is because you've found the last occurrence, but you can't know that when the arrows are grey no matter what. They should switch between grey and black, like the history arrows above.
Plus it would be useful if, when you come to the end, you got a popup asking you if you want to continue searching from the beginning, like you do in a word processor.
And while you're at it: if you could get the contrast between the grey and the black arrows a bit better it would be appreciated. It's certainly better than for the find arrows, but still a bit hard to see for my eyes.