^ man fluxbox-apps is your friend.
@vastone - I find auto grouping (tabbed windows) to be more efficient if you have a lot of windows open - like tabs marking important sections of a book. In the screenshot, internet apps and the terminal are set up in their own groups. Alt-Tab does the usual switching of open [grouped] windows, Win+Tab switches between tabs in a given group. The entire group can be manipulated - iconified or moved to a different desktop etc. Groups can also be customized. My internet group is always maximized and has no window decorations - Alt+F4 closes a window, or tab within a group.
If you prefer to not use the fluxbox iconbar, you can use the apps file to have all wwindows grouped and maximized and just use the tabs - configure fluxbox to have the tabs in the titlebar to save some vertical space.
Takes some getting use to - I actually find it better to use key binding instead of the mouse - but tabbed windows become a real time saver.
And tabbed windows are so much better than tiled windows IMO because you don't lose the original aspect ratio of the window.
tabbed windows in fluxbox:

For the curious - fluxbox, i3, and pekwm all support tabbing/grouping out of the box with straight forward configuration.
And a quick hack - all apps in one group, default decoration=tabs, maximized by default, tabs on right, no iconbar or panels:

fluxbox apps file opened in emacs - some grouping examples visible.