Thank you for the information on Clear-Jel. I've never heard of it but googled it and read that it was a modified cornstarch that can withstand the heat of canning (as mentions by the previous poster). I think I'd like to get some.

I sift a little flour in with the sugar and gently mix the fruit.
I never considered cornstarch for pies because I was told that, unlike flour, cornstarch breaks down easily - losing its thickening ability. I guess that's not a problem unless the pie is going to be around for a few days.
I use cornstarch as a thickening agent in Chinese dishes though. Flour gives the juice/gravy a pale color (This from my Chinese daughter-in-law) She teaches me Chinese cooking and I teach her Soul food (haven't converted her to chittlin' though, but her mother loves them).

Check out cream of tartar I believe that also can be used