void gtk_widget_modify_bg ( GtkWidget* widget, GtkStateType state, const GdkColor* color )
Sets the background color for a widget in a particular state.
All other style values are left untouched. See also gtk_widget_modify_style().
Note that “no window” widgets (which have the
GTK_NO_WINDOWflag set) draw on their parent container’s window and thus may not draw any background themselves. This is the case for e.g.
To modify the background of such widgets, you have to set the background color on their parent; if you want to set the background of a rectangular area around a label, try placing the label in a
GtkEventBoxwidget and setting the background color on that.