Select Keys

The playhead button serves as a grow button. Press it once to select the keys on the playhead, it will search for the nearest key if none exist there. Repeated pressings collect more keys, holding cntrl reverses the selection.

 

The next keys take the selection in either direction, holding shift also grows the selection.

 

Select all in either direction does exactly that.

 

The Select all key collects all the keys, the button also inverts the selection when Alt is pressed.

 

There is also a visibility toggle to more easily isolate location, rotation and scale in the graph editor.