Wash rhubarb, cut away any tough parts and chop into small pieces. Slice the strawberries and add to rhubarb. Mix the remaining ingredients and add to fruit. Blend well and allow to stand for up to 30 minutes to allow sugar to penetrate strawberries. Pour mixture into 23 cm pie crust, dot with margarine and cover with second crust. Cut slits in top crust. Bake in preheated 375-degree oven for 50-55 minutes. Cover pie with aluminum foil tented over it during first 30 minutes, removing to allow crust to brown during the last part of baking. About 10 minutes before done, brush on warm milk and sprinkle top crust lightly with sugar if desired.