The same old way as before, Grommok.
I didn't say the option to craft 1 gunpowder vanishes, only the option to craft 10 gunpowder disappears, when you have 9 minerals left in inventory.
Also, aFT, my part of the suggestion is to avoid FixBoy cluttering, but yeah, 10 items would be enough, because one can't carry that much minerals anyway.