Mix the first 3 ingredients in glass casserole or cake pan that will fit in your microwave. Use glass dish (Mom used to use a Corning Ware 2 inch deep large dish). Cook on high for 3 minutes, rotate dish - unless you have a turntable. Then cook for 3 more minutes on high. While that is cooking, stir together margarine, flour, brown sugar, cinnamon, and quick oatmeal. Mix well and put on top of rhubarb mixture. Microwave on high for 10 minutes - rotating once if you do not have a turntable.