Expander set optional column

If a tree view has optionals column (and is not draggable), the expander is put on the fake optional column instead of the first visible column.

assigned to @ced

added tryton type::behavior + 1 deleted label

added 1 deleted label and removed 1 deleted label

it works fine

New review393751003 at https://codereview.tryton.org/393751003/#ps368151003

New changeset 209131c90254 by Cédric Krier in branch 'default':
Skip first column for optionals menu to set expander
https://hg.tryton.org/tryton/rev/209131c90254

added 1 deleted label and removed 1 deleted label

closed

New changeset 8b37a16dd4f3 by Cédric Krier in branch 'default':
Skip first column for optionals menu to set expander
https://hg.tryton.org/tryton-env/rev/8b37a16dd4f3