public final boolean hideOverlay(Region overlay) {
        LOGGER.trace("hideOverlay");
        if (blockingOverlaysShown.contains(overlay)) {
            return blockingOverlaysShown.remove(overlay);
        } else {
            return nonBlockingOverlaysShown.remove(overlay);
        }
    }
Hides the {@code overlay} together with its {@link GlassPane}, which has previously been shown
using {@link Workbench#showOverlay(Region, boolean)}.

@param overlay to be hidden
@return true if the overlay was showing and is now hidden
@implNote As the method's name implies, this will only <b>hide</b> the {@code overlay}, not
remove it from the scene graph entirely. If keeping the {@code overlay} loaded hidden
in the scene graph is not possible due to performance reasons, call {@link
Workbench#clearOverlays()} after this method.
workbenchfx-core/src/main/java/com/dlsc/workbenchfx/Workbench.java