I am having diffculty if i try to type in the name of a field into the source box.  

 

It should be possible to type in the name of a field to put it into the source box.  But it seems that for the most part IQ jumps to the first field that begins with the letter typed in.  But even that is not consistent.  If I type in the letter I, the source box fills in with [Item Modified] but that is not next to the other "I" fields.  If I type "j", the source box may fill in in with "[j" but if I next type in in "k", the dropdown list does not jump to the "k" fields but rather displays "[jk".