Dropdown for search

Hello
Thanks for your plugin.
I’ve just purchased your “location map” addon, and after some cache issue, all is good with maps.
Now I would like to set a dropdown (select) input for my custom search.
I use this shortcode for search : [pdb_search template=default3 target_instance=2]
And in my template, I modify line 53 to :
$this->column_selector(false, true, 'metier2', 'column');
Because I just want to search the field metier2.
But in my database, metier2 is a dropdown. How could visitors find a dropdown search input instead of a text search input ?
Thanks !

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