When you are composing transaction, you see on the right all output addresses. The change address is represented by path and it is sent by myTrezor wallet to the Trezor device as this path. This is why Trezor doesn't show anything, because it knows, it generates that address itself from the seed.
If the Trezor works with same algorithm - it's fine.
If the developer could confirm it ("The change address is represented by path and it is sent by myTrezor wallet to the Trezor device as this path")
But as i wrote for other people can be strange that transaction has 2 outputs and they saw only one address & value when they signed the transaction.
Yes, i see, it's better (not show change address) for easy using of the Trezor. May be it should be as option in software which comunicates with the Trezor
> You can pregenerate this internal address by using account xpub and the shown path on bip32.org.
> If you give this address to Trezor explicitly and fill in the right change ammount,
> you will have to confirm it on the screen as with every other external ouput. Trezor doesn't recognize it as internal address when it is not sent as a path to it.
It's interesting test. But it not gaurantee that the path change address algorithm there works.
There may be there other alogorithm - change address are marked in program interface by special bit for example. If you enter address manually - there no bit, if computer calculate change address based on xpub - there is bit. But it will be bad algorithm.
I hope that change address is calculated inside Trezor based on sent BIP44 path of address.
You find it strange, because you were raised in environment, where it was necessary to check where "the rest of BTC" go. But this is in fact unnecessary. You have a wallet that has many addresses. In the scenario where you are spending to 10 output addresses, what SHOULD happen is that you should confirm those 10 addresses and the rest of BTC go back to you. That's it. The change depends on the inputs chosen by the algorithm. Imagine you have 1 BTC on 5 addresses 0.2BTC each. If you are spending 0.5BTC, then 3 inputs are used and the change is 0.1BTC. It may be even more confusing to a unexperinced user expecting change to be 0.5BTC. Since it can be arbitrary number going to your own address there is no point confirming it as many people already told you.
All addresses are (edit:)BIP44 compliant so it is really the same algorithm used on the web wallet and Trezor. There is no question about it.