




non-focus-maybe-capture-gesture ( non-focus-interface non-focus-list-interface) gesture
The generic function non-focus-maybe-capture-gesture needs to return non-nil if the gesture 
gesture
 was captured, which means it should not be processed any more, or nil if 
gesture
 was not captured.
gesture
 should be a gesture specifier, which is an object that can be coerced to a Gesture Spec by sys:coerce-to-gesture-spec.
The method on non-focus-list-interface does the following:
Escape it calls non-focus-terminate on the non-focus window.:gesture-callbacks or :add-gesture-callbacks, or implicitly. By default, all the gestures that are used in in-place completion (see  In-place completion) are defined implicitly. These include Up, Down, PageUp, PageDown (selection in the list panel), Return (action), Control+Return and Control+Shift+Return (control of the filter). The implicitly defined gestures are affected by 
gesture-callbacks
, 
filtering-gesture
 and 
filtering-toggle
. If a match is found, it is invoked as described for gesture-callbacks in prompt-with-list-non-focus.
The last character in the filter is deleted
One of the gestures which update the state of the filter (by default Control+Shift+R, Control+Shift+E, Control+Shift+C)
The state of the filter is updated.
In any case, where a gesture is captured by the filter the list panel is updated.
If the gesture is captured by one of the possibilities above, the method returns t, otherwise it returns nil.
CAPI User Guide and Reference Manual (Unix version) - 25 Feb 2015