Setting the new config variable "screen_switcher_browser_only" to "no"
will make the "key_screen_switcher" key switch between the current and
the last used screen, sort of like the Alt+Tab window switching
mechanism in many window managers.
This (intendedly) works only for the "main" screens (playlist, browser,
media library, etc.) and not for info/lyrics/server info. Those screens
can be closed with the screen_switcher key, but the will not be
remembered.
indentation correction in config
