customizing the NSPredicateEditor

I want to customize the NSPredicateEditorRowTemplate, but I needn't the subtraction sign in the first RowTemplate, the second, and the third, like the Finder app开发者_JS百科lication.

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If you tell the NSPredicateEditor that it cannot remove all the rows in the editor, then the editor will automatically remove the (-) button when necessary.

You can do this by unchecking the "Can Remove All Rows" checkbox when editing the predicate editor in a xib, or by doing it programmatically with the -setCanRemoveAllRows: method.