Does anybody know if it's possible to associate a filetype with a specific application?

I have several excel files that open fine in Gnumeric, but ideally, I'd like to be able to navigate to the file in File Manager, click on the file and have it open Gnumeric with the file loaded. Currently, I can tell it to use Gnumeric, but all it does is start Gnumeric, not load the file. I still have to use "File... Open" within Gnumeric.

Thanks.

R.
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