Hide a feature to get at GPS tracks beneath

I’m a new user who wants to add in some bike paths in my town from uploaded GPS data. I’m using Potlatch. There is a feature—an “administrative” boundary that delimits the city border—that is directly over much of my track hiding it. I can’t even tell if someone else has already added the bike path because of this boundary (it’s very thick: a gray line surrounded by light purple on both sides).

Is there a way to hide this boundary while I’m editing? Or to get the GPS tracks on top?

Added: Also, it it generally preferred touse my GPS tracks or the underlying Yahoo! image? They differ slightly.

Thanks.

Does the option to use thinner lines for areas help?
For the latter: unless the path has been realigned, the aerial should be more precise.

Caps lock also fades everything out which should help you see your GPX track better.