I've often wondered if a Suntour XC front derailleur could be modded to work with Shimano thumb shifters. I think it all comes down to cable pull and attach point on the derailleur. By attach point, I mean routing the cable to the opposite side of the bolt, or even through the bolt, like the old road brakes. It might mean extending arm, which would get pretty creative. But you need to figure out the difference in cable pull between Suntour and Shimano to know if it is possible.

John