Currently, the Show/Hide state of sublayers (e.g. Markers, Overlays) in a Project is found either by scrolling through a lengthy list in the Layer Size/Visibility Preference or by examining one-at-a-time the individual sublayers (e.g. Markers in the Edit Markers window). Example Suggestion: Gray-out the name of each Hidden Marker in the entire list of Markers in the Edit Markers window, distinguishing the Show/Hide state of every Marker at a glance. This suggestion has perhaps greatest value for Overlays in a complex Project.
This suggestion does not require revising the always-visible GUI as proposed in this forum "layer display palette on the left sidebar".
See related suggestion "Visible (with single-click) listing of Layer Type Show/Hide status".