Maxthon 2 introduced a nifty feature called Magic Fill, this little tool can fill forms with pre-saved data either login information for websites or personal information in registration forms (from what you fill in the Setup Center).
Play button opens the website then fill and submit the login form
Unlike Opera’s Magic wand (and a lot like Roboform’s feature “fill and submit”) you can with Magic fill save time opening a website, clicking the fill button and clicking the submit button by using the sub-menu of the Magic fill button to access your favorite websites, this way it only needs one click to open the site, fill the data and then submitting it.
Clicking the item itself opens the website and fill only while the little “play” button on the right of each item works as a “fill and submit” option.
You can choose what sites you would like to keep in this menu by putting a “tick” next to them in Tools > Maxthon setup center > Magic Fill
Maxthon Setup Center's Magic fill section
Maxthonology 
Cool! Never realised the play button was a separate entity. Pity it can’t be keyboard shortcut, but that’s still put it on a par with RoboForm.