Visible (with single-click) listing of Layer Type Show/Hide status
Here is an alternate proposal that avoids the need to modify the Compass Bar or GUI as suggested in "layer display palette on the left sidebar". The idea here is to give an easy frequent view of the Show/Hide status of often-edited Layer Types with a single click and should be possible to implement without needing a major redesign of the GUI: Simply have the Layer Types in the Layers dropdown grayed-out if Hidden. Then every click on the Layers button offers a quick, intuitive, unobtrusive reminder of the Show/Hide status for these frequently-used Layer Types.
This proposal does not change the functionality of the dropdown. However, functionality may be extended (but still intuitive to use) by including for each Layer Type a box, X'd or open, to indicate and change (with click) the Show/Hide state (same as in the Layer Size/Visibility Preference).
These proposals apply globally to Layer Types, not Project- by- Project sublayers, same behavior as Layer Size/Visibility.