Multiple select in the aggregate filter drop downs

[cjohnsonuk]

Feature Description

When using the aggregate filters syntax described here https://www.dokuwiki.org/plugin:struct:aggregation:filter

and looking like this

---- struct filter ----
schema: my_products
cols: product_name, product_type, tag, colour, length, width, height

I'd like to be able to select multiple entries from the filter drop down lists so that I can be more flexible in how my data displays, eg side by side comparison of 2 products but only ones that are colour red or colour blue.

I've tried selecting multiple entries in the existing lists but it doesn't appear to work.