This idea is considered a "frequently asked question", but I am hoping it will resurface the Esri technical development team's list to priorities. In Exp Builder, currently only one sidebar works with a Map. While you can add a second sidebar (i.e. on the opposite side), the empty space where the map is typically placed interferes with the empty space of the first sidebar. Therefore, features in your map become unresponsive because the empty space of the second sidebar overlays that portion of the map.
In a nutshell, having two sidebars would be great.
