existing option chain button on QAT - the QAT button you refer to is one from the Add Option button on the ribbon, and no, that will stay the same.That is the selector for a single option symbol.
Option chain window on top setting - fixed. It is now like the charts, raw data, etc.
column sizes - will have to get back to you on that
Vertical Spread trading - right now MT does not support complex options trading, so we did not enable that capability from the option chain. When we add that to the trading, we will make it so it can be traded from the chain window.
Colors - MT is using the stripe row color for ITM options. Some color sets don't have that much distinction for the stripe row. I don't want to modify existing color set's stripe row color since that impacts more than just the chain. I made it so I can override that for specific color sets and made Silverback and Night a bit lighter background for ITM.
Delete in portfolio = right click, select CUT - does the same thing. Also SHIFT+DEL does it.