CANADA STOCKS-TSX down on weaker commodities, euro zone doubts

* TSX down 13.53 points, or 0.1 pct, at 11,901.90 * Materials, financials lower, energy flat By Jon Cook TORONTO, Nov 18 (Reuters) - Toronto's main stock index was down slightly at midday on Friday as resource and financial issues fell on concerns that European policymakers were not acting urgently enough to resolve the debt crisis. Commodity stocks looked to rebound after their biggest selloff in nearly two months on Thursday, but were restrained by the European Central Bank's