Changing default window and pane sizes and position

When I start Mailspring, the window opens in a default position and size, and the panes likewise open in default sizes. Then I change these. Is there a way to have Mailspring remember the window position and size, and the panes’ sizes, so I don’t have to modify these each time I start the app?

Also, I would like not to see the pane on the far right that shows the sender and recipients. Can I get rid of this and have Mailspring remember that choice?

Thanks for any help.

Not a very active community, I guess.