I want to add a comment which may apply to the opening tabs in background / foreground issues.
Although I have left MX6 due to too many bugs and have reverted to MX5, there was a similar issue with TABs opening in the background. In my case, when I clicked on a link which was designed to open in a new tab, that tab opened in the background (Maxthon didn't switch to it immediately, I had to click on it). I wanted it to be switched to / focused / displayed immediately when I clicked on the link, even if it opened in a new tab.
I distinctly remember that this worked correctly before, but after I upgraded to MX6 and then downgraded to MX5, it didn't work anymore.
There used to be an option called "Open a new tab in the foreground" in "Settings -> General -> New tab action" which I must have activated in the past. However, in their infinite wisdom, developers removed this option in later versions of Maxthon 5 (and probably Maxthon 6). So I could not activate it again in Maxthon 5.3.8.2000 or 5.3.8.2100-beta.
Luckily I had an archive of old Maxthon versions and I installed 5.1.7.2000 and that one still had this option. I activated it and then installed 5.3.8.2100-beta again. And now newly opened tabs are focused again!
So it seems that settings like these are saved somewhere in the registry and if the option is removed in future versions, the setting can't be changed anymore, although Maxthon still reads and uses it.
Maxthon 6 may well be inheriting some of the MX5 settings and since you can see how much less of them there are in MX6, you can imagine a lot of things are unchangeable now. You may want to give it a try yourselves if you have similar problems.