[gtkmm] Horizontal expand list view

[Gavril Razvan <rgavril home ro>]

I want to make a tree view whit a single column, but instead of using a 
Vertical Scrollbar for the parent widget(when the list don't fit) i want 
it to add a second(third,forth..) column so the scrolling will be only 
horizontaly. Any ideeas how that can be posible? I tried adding the 
treeview into a ScrolledWindow and check 
ScrolledWindow::get_vsrollbar_visible() but returns false all the time, 
even if vscrollbar is visible.