The intent of the [+] and [-] buttons in the "filters" and "actions" buttons isn't clear. For instance: - why does the first line have a [-] suggest looking at alternative ways of handling this, such as a mail-tools filter rules.
The first line has a [-] because clicking that button while it will not remove the row it will remove the filter it represents from the observer. It will also clear the selection boxes and the arguments Entry. This patch also changes it so that the button is grayed out once it has removed the filters, and cleared the feilds. This is exactly what is done in Thunderbuird to edit filters. 2007-03-20 Sami Wagiaalla <swagiaal@redhat.com> * ObserverItemRow.java : [-] Button now disables itself when there is only one row is left and the represented filter has been removed from the underlying Observer. Fix for bz 4159.