[UI/UX] Notify of delisting of asset in advance

Currently if I'm trading asset X and it gets delisted, there's no warning telling me so. As of writing this, the asset Zcoin (XZC) appears on the "Delisted due to inactivity" list and can't be selected from the altcoin dropdown menu under Settings > Preferences. But it is one of the default altcoins so it appears under the already selected altcoins. Even worse than that, it still appears under the BUY BTC and SELL BTC tabs and the market remains remarkably untouched: the ability to create and see offers remains untouched.

It'd be better if:

• the creation and broadcast of offers for delisted assets were prohibited
• there were a warning that an asset is soon to be delisted