Problem with grids and items spanning more than one column

[Mike Martin <mike redtux plus com>]

I am using an embedded Gtk grid within a grid , which contains numerous
widgets
However if I have a widget that spans more than one column it messes up the
layout of all other widgets , which seem to position themseleves randomly
along the width of this widget, causing horribly jagged widget placement

Has anyone had this and come up with a solution

example png attached
The multicolumn widget is is the file liststore
Then I have the second liststore on the next row with other widgets on the
same row

Mike