Preheat oven to 350°F.
To make crust, mix flour, oatmeal, brown sugar, cinnamon, and melted butter until crumbly. Press 1/2 of the mixture into the bottom of a 9x9 inch pan.
Cover with chopped rhubarb, then sprinkle with dry Jell-O. In a medium saucepan, combine white sugar, cornstarch and water. Cook until thickened and clear. Add vanilla. Pour over rhubarb, pat remaining crumbs on top.
Bake at 350°F for 1 hour.
Submitted by: Tootswil