Remove an item from the collection.
@param {Object} o The item to remove.
@return {Object} The item removed or false if no item was removed.
@since Ext 1
function(o) {
        var me = this,
            removeKey,
            index;

        // If
        //     We have not been forced into using linear lookup by a usage of the 2 arg form of add
        // and
        //     The key extraction function yields a key
        // Then use indexOfKey. This will use the indexMap - rebuilding it if necessary.
        if (!me.useLinearSearch && (removeKey = me.getKey(o))) {
            index = me.indexOfKey(removeKey);
        }

        // Otherwise we have to do it the slow way with a linear search.
        else {
            index = Ext.Array.indexOf(me.items, o);
        }

        return (index === -1) ? false : me.removeAt(index);
    }