After losing Old Ironjaw again, I got frustrated and decided to attempt a fix.
I'm using FishermansFriend for doubleclick casting. I haven't seen any kind of attempt to fix this problem anywhere, so thought i might aswell share.
I've included the change here:
http://devcub.com/~adys/FishermansFriend.zip
If you don't use FMF and can find yourself in a Lua file, just include this snippet at the start of the cast function (likely an OnClick):
if StaticPopup_Visible("LOOT_BIND") then return print("Loot before recasting!") end
Didn't have the occasion to test the change, but it should work and not cast anything if the BoP confirmation box is up. I'd test with Old Crafty but I don't have the daily atm and I'm alliance. If someone could do that.. would be great.