I don't know if it is bug or feature.
I expect that readonly attribute should only restrict user from setting value that is not present in comboitems. But it also restrict me from choosing value by writing text value.

ZK Fiddle: http://zkfiddle.org/sample/15b2kl1/3-Readonly-combobox

• try to open Combobox and choose value by writing text 'ab' for select 'abbbbbbb' value

expected result:

after writing 'ab' item with value 'abbbbbbb' is highlighted

actual result:

after writing 'a', next item starting with 'a' is highlighted, after writing 'b', nothing happens