I just noticed a possible bug or interaction problem with 1Password- Version 5.3 (530029) - Mac App Store and Firefox 37.0.2.
I had two windows open. The login form that appeared had the two username/password fields with the cursor within the filed and the window had focus, but 1Password insisted on filling in a random field on the window in the background.
I wish I could show you, but both sites are behind our firewall. They are using commercial/opensource applications (Zenoss Monitor and BMC Software - BMC Footprints ticket software).
The up front focus window received no input, just the window behind it. I had a ticket open (the second window) and remembered I needed some information from Zenoss to put into the ticket, opened a new tab, opened the site and tried to login, but 1Password would do the above.
Grr.. Anyone else seen this? I bit of helpful information, BOTH windows have a URL loaded that is listed in the "login" URL list on the 1Password entry. However this one entry is UTEID, the common single-login system for Univ. of Texas. So I keep adding URLs of sites that request those credentials (which is what I thought I was supposed to do?)