It would be nice if I can determine the position of the tab in the tkk::notebook
e.g: -tabpos [e|s|w|n]
I need this to have many tabs and to use the lage width of the screen.
That would seem to me to be at best a feature of the style/layout, and not an option that's fully exposed by default...
There is partial support for this in CVS HEAD (see Bug 1470246 for details) -- the ttk::notebook widget can place tabs on any side (style option -tabplacement, same semantics as ttk::labelframe -labelanchor option, which in turn is a generalization of the core labelframe -labelanchor option).
However, none of the common themes currently support down-, left-, or right-ward pointing tabs, so anything other than -tabposition "n/nw/ne/new" will look wrong.
This last bit is easy to implement for the XP theme, something of a PITA for clam, alt, and simple, and of completely unknown difficulty for aqua / hitheme.