Sewing Project number three... :D

[sharpiefan]

Just finishing my new breadbag (to go with my new trousers and still new-looking red coat - at this rate, nobody's going to believe I've been in the hobby for more than a couple of months, let alone nine whole years!), and I need to make the buttonholes in the flap and add the buttons.

Now, I've had a problem with my buttonholes pulling out before now so my question to you lovely people is: What thread do you use when buttonholing?

I'm using a light-weight cotton drill, a bit lighter than denim weight.