A maximized window cannot be dragged in most window managers.
The area above the tabs where you can click to drag or double-click to restore is pretty narrow - people who want to run Opera maximized prefer it that way so the tabs go all the way to the top of the screen. Since you don't appear to want to run Opera maximized, you could go to opera:config and set "Chrome Integration Drag Area Maximized" to a larger number (at least 5) to make it easier to find the right area.
Inappropriate - that is, not related to Opera or Linux. Try a web design forum. And if you post another link to your site, you will be banned as a spammer.
I'm happy to report that this issue is resolved! Per the advice I got here I contacted FastMail support &, after sending them screenshots of the nag pop-ups, they had me check Opera's "Mail & Chat Accounts..." [from "Tools"]. Sure enough, my wife's email address was there although it didn't belong there. I deleted it & that resolved the problem. Apparently my wife accidentally put her email address there when she responded to a pop-up dialog box that she probably got after hitting the wrong key combination. Thanks for your efforts.
I just installed this on Linux mint cinnamon 14 Nadia. Everything that has been broken for me is fixed so far. Enormous amounts of time fixing speed dial up, and getting tabs to open on start up. Hate the menus that are gone. Zendesk memory leak is gone now too, which used to cause opera 12.16 to crash. Flash doesn't seem to work. Where it was no problem on 12.16. We'll see how this plays out. I have already received one update in a week to this dev version. So glad having to use FF or chrome for this and that is over, and I can kick them to the curb. Hope this thing goes full support soon. How can we as a community help?
It is one of maybe half a dozen commonly used sites around here and one of the less obnoxious ones. Do not use (or suggest) a site with ads for adult//dating sites or with too many ads, other than that I wouldn't worry about it. (I have an account on Flickr so I use them, but otherwise ... I have seen some sites used that have access problems and wouldn't recommend those either.)