as per Isthiriel:

this request is for that every field in the filter dialog should have its counterpart in text form, for example

I could create a search for English multicolor rares in NPH with cmc >= 3

or I could write

"c:m mana>=3 r:rare e:nph/en"

into the quick search field.

this is already implemented at magiccards.info

see also #63 (boolean queries)