When you type some keys into an AutoReducible ComboBox the item list in the popup under the ComboBox contains a reduced set if items. You can choose one with a mouse click. If instead you use the "cursor down" key to access these items the first one is selected. But at the same moment the list is changed to be unfiltered. If you want to select the second item from the reduced list you can't do that.
idempiere head, java7
I did a contribution at https://bitbucket.org/tbayen/idempiere/commits/9034b3517d05d8b9ab5be15d0d6034caff484267
This patch was so small and easy that I wonder why it ws not done earlier by someone else. Please tell my why this does not work.