If a field is from type Button you can start a process by pressing this button. Some processes affect the shown record and some affect many or all records. This button shall not be in the record's input form (like now) but in the Toolbar. That is a better place to start processes - especially if they deal with more than just the shown record.
This is implemented in zk Client since IDEMPIERE-234. (I want to implement the rest of zk functionality for Swing later.)
Carlos Ruiz told me this issue is described at http://wiki.idempiere.org/en/NF001_ColumnToolbarButton
After the weekly meeting I found a bug with the usage if isToolbarButton() and I improved the menu behaviour.