To make the crust: In a bowl mix together, the oatmeal, brown sugar, flour, and salt.
Cut in the pieces of butter, with either a fork or pastry blender, until mixture becomes crumbly (like a streusel topping).
Press half of the crumb mixture into an ungreased 13x9x2-inch glass baking dish. (I probably added 2/3's of the crumb mixture.)
To make the filling: In a large saucepan (I used a 3-quart saucepan), add the granulated sugar, cornstarch, and water. Stir until blended, then bring to a boil over medium-high heat; stirring continuously, and until the mixture thickens. The mixture should thicken within 3 minutes. (At least mine did.)
Once the mixture has thickened, thoroughly stir in the extracts and pie filling.
Now spread the rhubarb over the crust, then spoon the cooked pie filling on top, and sprinkle on the remaining crumb mixture.
Lastly, top the crumb mixture with the chopped pecans.
Bake in a 350º oven for 45-55 minutes. (I baked mine for 55 minutes.)
Serve warm with vanilla ice cream. (Refrigerate any leftovers.)
Enjoy refrigerated leftovers with either Reddi Wip, or Cool Whip Whipped Topping.