If I use Krunner and begin typing, then matching results are displayed immediatly when part of the string is matched, like "fir" brings up "firefox" as suggestion. But with files, I always have to add a "*" (which is inconvinient because of the extra shift-key needed to add the "*" and new users will forget to add the "*", because of krunner start already showing results without the "*").

Any way to adjust this behaviour, so krunner starts listing files without the need to add an "*"?

Do you have the "Nepomuk Desktop Search Runner" enabled?

ah yes, now its listing stuff as I type, thanks