[gtkmm] hiding/disabling/setting toolbar buttons?

[Maurizio Colucci <seguso forever tin it>]

hello, 


for the file manager http://segusoland.sourceforge.net ,
I have a toolbar and I am adding togglebuttons with

aToolbar.tools().push_back(Gtk::Toolbar_Helpers::ToggleElem(
							   aText,
							   *lImage,
							   SigC::slot(*this, &SegToolbarToggleButton::onElementToggled),
							   aTooltipText));

I couldn't figure out 
1) how to set the pressed state of the toggle element via code.
2) how to show/hide the toggle element.
3) how to disable/enable it.

Maybe I have to add the item via toolbar::append_item, and act on the returned 
Widget*? But how do I create a toggle button via append_item?

Thanks for your help,

Maurizio