[gtkmm] Change a Widget's background color

[Báthory László <bathory enternet hu>]

Hi!
I would like to change a widget's background color. 
I tried widget.get_modifier_style()->set_bg (RcStyle)
or get_style's set_bg but as I use it doesnt work for me at all.
Please send me a working example (I want to change only the bg color)

Thanks in advance
morti