Placing grid

[Abdoulaye Walsimou Gaye <walsimou walsimou com>]

Hello list,
I want to place a grid line on every number in rulers created by
gtk_databox_create_box_with_scrollbars_and_rulers().
I know that I get those rulers by using gtk_databox_get_ruler_{x,y}()
and then get lower, upper, position propeties by using
gtk_databox_ruler_get_range(). But I think I don't have enough data to
place my grid lines!
How to know the space between each number in a ruler?
In the current gtk-tutorial about rulers, they talk about 100 pixels
between numbers (?), does this
applies in case of GtkDataboxRuler? And if so, how to convert those
value in pixels to a real double number in order
to use gtk_databox_grid_array_new() to place my grid lines?

Thanks in advance for any comments/help!
Best regards,
AWG