Dashboard Types || Custom Control - v7.4
With v7.4, it's now possible to create separate Maintenance Units, to isolate a "solution". But with that also the new "Dashboard Type" have arrived, including "Custom Control", but also a new Navigation Action on a button, called: "Forward Custom Control Action to Parent Event Listener"
Anyone have experience in how this works, or where I can find more documentation or examples of the functionality
A custom control is basically just a dashboard that is meant to be reusable by different embedders. As such, it formalizes the inputs and outputs that it can provide. There is a description of its properties in the online help, if you search for "Embedded Custom Control Dashboard"; the option you highlight here basically triggers the passing of selected values to the parent embedding dashboard.
Examples at the moment are a bit scarce, since the whole Workspaces vision is still somewhat incomplete. It will (or rather should) be explained a bit more once the new BrowserUX lands fully.