First look at the Layer Control tool and its HTML menu:

Fairly simple really. Just a bunch of sliders that allow one to incrementally change the visibility of the layers of the plugins.
I now need to add in a visibility option/integer for each layer in each plugin which can be adjusted within the global settings of each plugin.

Fairly simple really. Just a bunch of sliders that allow one to incrementally change the visibility of the layers of the plugins.
I now need to add in a visibility option/integer for each layer in each plugin which can be adjusted within the global settings of each plugin.