Private Called after a new record has been navigated to by a keystroke. Event is passed so that shift and ctrl can be handled.
function(e, record) {
        var me = this,
            recIdx,
            fromIdx,
            isSelected = me.isSelected(record),
            from = (me.selectionStart && me.isSelected(me.lastFocused)) ? me.selectionStart : (me.selectionStart = me.lastFocused),
            key = e.getCharCode(),
            isSpace = key === e.SPACE,
            direction = key === e.UP || key === e.PAGE_UP ? 'up' : (key === e.DOWN || key === e.DOWN ? 'down' : null);

        switch (me.selectionMode) {
            case 'MULTI':
                
                if (isSpace) {
                    // SHIFT+SPACE, select range
                    if (e.shiftKey) {
                        me.selectRange(from, record, e.ctrlKey);
                    } else {
                        // SPACE pessed on a selected item: deselect but leave it focused.
                        // e.ctrlKey means "keep existing"
                        if (isSelected) {
                            me.doDeselect(record, e.ctrlKey);

                            // This record is already focused. To get the focus effect put on it (as opposed to selected)
                            // we have to focus null first.
                            me.setLastFocused(null);
                            me.setLastFocused(record);
                        }
                        // SPACE on an unselected item: select it
                        else {
                            me.doSelect(record, e.ctrlKey);
                        }
                    }
                }

                // SHIFT-navigate selects intervening rows from the last selected (or last focused) item and target item
                else if (e.shiftKey && from) {

                    // If we are going back *into* the selected range, we deselect.
                    fromIdx = me.store.indexOf(from);
                    recIdx = me.store.indexOf(record);

                    // If we are heading back TOWARDS the start rec - deselect skipped range...
                    if (direction === 'up' && fromIdx <= recIdx) {
                        me.deselectRange(me.lastFocused, recIdx + 1);
                    }
                    else if (direction === 'down' && fromIdx >= recIdx) {
                        me.deselectRange(me.lastFocused, recIdx - 1);
                    }

                    // If we are heading AWAY from start point, or no CTRL key, so just select the range and let the CTRL control "keepExisting"...
                    else if (from !== record) {
                        me.selectRange(from, record, e.ctrlKey);
                    }
                    me.lastSelected = record;
                    me.setLastFocused(record);
                }

                // CTRL-navigate onto a selected item just focuses it
                else if (e.ctrlKey && isSelected) {
                    me.setLastFocused(record);
                }

                // CTRL-navigate, just move focus
                else if (e.ctrlKey) {
                    me.setLastFocused(record);
                }

                // Just navigation - select the target
                else {
                    me.doSelect(record, false);
                }
                break;
            case 'SIMPLE':
                if (isSelected) {
                    me.doDeselect(record);
                } else {
                    me.doSelect(record, true);
                }
                break;
            case 'SINGLE':
                // Space hit
                if (isSpace) {
                    if (isSelected) {
                        me.doDeselect(record);
                        me.setLastFocused(record);
                    } else {
                        me.doSelect(record);
                    }
                }

                // CTRL-navigation: just move focus
                else if (e.ctrlKey) {
                    me.setLastFocused(record);
                }

                // if allowDeselect is on and this record isSelected, deselect it
                else if (me.allowDeselect && isSelected) {
                    me.doDeselect(record);
                }
                
                // select the record and do NOT maintain existing selections
                else {
                    me.doSelect(record, false);
                }
                break;
        }

        // selectionStart is a start point for shift/mousedown to create a range from.
        // If the mousedowned record was not already selected, then it becomes the
        // start of any range created from now on.
        // If we drop to no records selected, then there is no range start any more.
        if (!e.shiftKey) {
            if (me.isSelected(record)) {
                me.selectionStart = record;
            }
        }
    }