Click '+' button to open, '-' button to close, '++' button to open all, '--' button to close all.

Clear all selected keywords by closing the tree and opening it again with the '+' button.
Alt-click '+' searches the current keywords in the tree.
Control-Alt-click '+' searches the keywords of the current slide.

Alt-click keyword selects a keyword without broader terms or deselects a keyword with broader terms.

Selected keywords are available in the Clipboard.

'nei' stands for 'not elswhere included'.