Change background color in GtkTreeView

[Tomasz Jankowski <tomcioj gmail com>]

Hello,

I'm working on UI for embedded system using GTK+ 2.24. I want to
change GtkTreeView background (area behind rows, which is by default white)
to match default color of window area (grey by default).
I retrieved GtkStyle associated with GtkWindow and looked for this
particular tint of gray color in GdkColor arrays in GtkStyle instance
("gb", "fg", "base" arrays). Then I assigned these colors to GtkTreeView
using gtk_wdget_modify_base(), but I was unable to find the same color. Any
idea?