public final void hideDrawer() {
        setDrawerShown(null);
        setDrawerSideShown(null);
    }
Hides the currently displayed drawer that was previously shown using
{@link #showDrawer(Region, Side)} or {@link #showDrawer(Region, Side, int)}.
workbenchfx-core/src/main/java/com/dlsc/workbenchfx/Workbench.java