Every preference in about:config does not contain a space and the search bar also does not search the key values of the preferences. So if the search bar in about:config has a space in it, it should attempt to search strings that contain both strings, but not sequentially or connected. So if I were looking to toggle media key functionality in firefox, I would need to get the preference: media.hardwaremediakeys.enabled. I often don't immediately recall what the preference name is or how it is formatted off the top of my head, especially when the formatting is very inconsistent overall. If I search "media hardware" or "media key" it should display any preference containing both "media" and "hardware" or "media" and "key". If the preference contains the entire search string with spaces wildcarded or removed, it could also have preference towards the top of the search.