fix(background): multiple backgrounds, separate pattern ids closes #1037

example/src/index.tsx

@@ -25,6 +25,7 @@ import SwitchFlows from './Switch';
 import UseZoomPanHelper from './UseZoomPanHelper';
 import UseUpdateNodeInternals from './UseUpdateNodeInternals';
 import Undirectional from './Undirectional';
+import MultiFlows from './MultiFlows';
 
 import './index.css';
 
@@ -121,6 +122,10 @@ const routes = [
     path: '/undirectional',
     component: Undirectional,
   },
+  {
+    path: '/multiflows',
+    component: MultiFlows,
+  },
 ];
 
 const Header = withRouter(({ history, location }) => {