"Opera has a powerful multiple document interface (MDI), and Opera is very efficient with multiple open document windows. There are shortcuts for just about everything you need to do to manage multiple open documents.
Open a new document window with Ctrl+N.
Duplicate a window with Ctrl+Shift+N.
Reload all documents, Ctrl+F5.
Cascade windows, Shift+F5.
Tile all windows horizontally to fill the workspace, F6.
Tile all windows vertically to fill the workspace, Shift+F6.
Restore focus on current document window, F9.
Switch view to the next document window, 2 or Ctrl+Tab.
Switch view to the previous document window, 1 or Ctrl+Shift+Tab.
Minimize current document window, 4.
Maximize current document window, 5.
Close all open windows, Ctrl+Shift+W.
A very handy Opera feature is the Global history window. Open it with Ctrl+Alt+H.

Another fast, fun, and powerful functionality...
You can load the document under the active link into a new window using Shift+Space or Shift+Enter. If you would prefer that document to pop up in the background, so that it does not obscure the window that you are currently reading, use this instead: Ctrl+Shift+Space or Ctrl+Shift+Enter. If that window happens to yield nothing of interest, just close it with Ctrl+W.

New document window Ctrl+N
Duplicate window Ctrl+Shift+N
Reload all documents Ctrl+F5
Cascade windows Shift+F5
Tile windows horizontally F6
Tile windows vertically Shift+F6
View next window 2 or Ctrl+Tab
View previous window 1 or Ctrl+Shift+Tab
Minimize window 4
Maximize window 5
Close all Ctrl+Shift+W
Global history Ctrl+Alt+H" (Opera, <http://www.opera.com/support/windows/tutorial/nomouse/#windows>

So what is this, an advertisement for Opera? Opera's not a bad browser, however it renders pages incorrectly sometimes (and no, it doesn't have anything to do with HTML compliance), plus it's adware, bought to you by the *caring* people at Cydoor (http://www.safersite.com/PestInfo/C/Cydoor.asp).
Or is it such that you're trying to make, yet another attempt, at suggesting that *all these features* be incorporated into K-Meleon? Why don't you just cut to the chase and say "I want tabs", or more like others "I DEMAND TABS OR ELSE!!!!". ;-)

Mind you, tabs abd MDI are two totally different things. They may work hand-in-hand as in Opera (tab for each child) but they don't have to, neccessarily. Older Office progs used to be MDI, remember? I'd vote for tabs any time but against MDI just as firmly.

Opera originally had that Program Manager MDI interface, however the newer versions have veered away from it slightly, and now it is more like a tabbed interface. And guess what; the *new* feature they introduced with Opera is, drumroll please, the option to have an SDI interface. Now if MDI/tabs is so great, and the *way of the future* I might add, then why did the Opera programmers incorporate the SDI interface in the first place?
Anyways, I've just come up with a new marketing slogan for Opera: "Opera, where's the DOM?" Seems incorporating an SDI interface was higher on their list of agendas than adding in DOM support. ;-)

Ahyes, Opera

Opera is always late with its technology. It took 6 versions and god knows how many years to get utf-8 into Opera. Even Netscape 3 was possible to persuade to use utf-8. But not Opera. Until now. They're kind of reluctant with Javascript too and even more so with DOM. They're good adding wow-factor type things but always come up with 2 yrs behind actual web development :-P

As for them adding SDI then I guess its just the way ppl wanted it. It's great to have choice, isn't it?