[gtkmm] TreeView width?

[Igor Gorbounov <igorbounov voronezh serw ru>]

Hi, All!
Is there any reliable method for calculating the size of a filled
TreeView before showing it, for proper setting the size of a window
containing this treeview?
get_width() for TreeViewColumns returns 0, get_width() for the treeview
itself returns a significant lesser value, cell_get_size(...) returns
very small widths, pango_layout gives the proper values for text size
in cells, but it knows nothing about white spaces between columns and
I have to scan all rows for every column to get the maximum size.
So how normal folks are doing this?
	Igor Gorbounov