I have been a fan of Tree tabs for a long time. There is an extension for Firefox called Tree Style Tabs and it essentially displays the tabs in a tree-like fashion. I know what you're thinking, many extensions do indeed display the tabs vertically, but nothing has come close to the added functionality of a true "tree" tab structure for viewing tabs, and this is what I would like to see from QuizoApps is a true tree-tab solution.
Here are some pictures of what the Firefox Extension called Tree Style Tabs looks like. https://addons.mozilla.org/en-US/firefox/addon/5890 Perhaps this can be adapted to QTTabBar or a whole different tab solution, you could call it QTTabTree.
The font for those tabs is ugly, so don't pay attention to the ugliness factor of the fonts in that picture.
If need be, it could be adapted to look like mIRC's tree tabs. Here is a picture of what that looks like:

It doesn't have to look exactly like that, but it would definitely be a nice adaptation for tabs.
Also, think of the new possibilities of having a tab tree structure. You could organize the tabs based on a hierarchical nature. For instance, a tab for "D:\My Pictures" would be above "D:\My Pictures\Some Other Folder". Now it doesn't matter if you forget where your tabs are, you know they're always in order based on the address of the tabs.
Just something to consider! :)
Thanks,
-Neil
