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diff --git a/sdc-workflow-designer-ui/src/app/paletx/core/overlay/overlay.ts b/sdc-workflow-designer-ui/src/app/paletx/core/overlay/overlay.ts
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+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+/* tslint:disable:array-type member-access variable-name typedef
+ only-arrow-functions directive-class-suffix component-class-suffix
+ component-selector no-unnecessary-type-assertion arrow-parens*/
+import {DomPortalHost} from '@angular/cdk';
+import {ApplicationRef, ComponentFactoryResolver, Injectable, Injector, NgZone} from '@angular/core';
+
+import {OverlayContainer} from './overlay-container';
+import {OverlayRef} from './overlay-ref';
+import {OverlayState} from './overlay-state';
+import {OverlayPositionBuilder} from './position/overlay-position-builder';
+import {ScrollStrategyOptions} from './scroll/index';
+
+
+/** Next overlay unique ID. */
+let nextUniqueId = 0;
+
+/** The default state for newly created overlays. */
+const defaultState = new OverlayState();
+
+
+/**
+ * Service to create Overlays. Overlays are dynamically added pieces of floating
+ * UI, meant to be used as a low-level building building block for other
+ * components. Dialogs, tooltips, menus, selects, etc. can all be built using
+ * overlays. The service should primarily be used by authors of re-usable
+ * components rather than developers building end-user applications.
+ *
+ * An overlay *is* a PortalHost, so any kind of Portal can be loaded into one.
+ */
+@Injectable()
+export class Overlay {
+  constructor(
+		public scrollStrategies: ScrollStrategyOptions,
+		private _overlayContainer: OverlayContainer,
+		private _componentFactoryResolver: ComponentFactoryResolver,
+		private _positionBuilder: OverlayPositionBuilder,
+		private _appRef: ApplicationRef, private _injector: Injector,
+		private _ngZone: NgZone) {}
+
+  /**
+   * Creates an overlay.
+   * @param state State to apply to the overlay.
+   * @returns Reference to the created overlay.
+   */
+  create(state: OverlayState = defaultState, paneClassName?: string):
+		OverlayRef {
+	return this._createOverlayRef(
+		this._createPaneElement(paneClassName), state);
+  }
+
+  /**
+   * Returns a position builder that can be used, via fluent API,
+   * to construct and configure a position strategy.
+   */
+  position(): OverlayPositionBuilder {
+	return this._positionBuilder;
+  }
+
+  /**
+   * Creates the DOM element for an overlay and appends it to the overlay
+   * container.
+   * @returns Newly-created pane element
+   */
+  private _createPaneElement(className?: string): HTMLElement {
+	const pane = document.createElement('div');
+
+	pane.id = `nz-overlay-${nextUniqueId++}`;
+	pane.classList.add('nz-overlay-pane');
+	if (className) {
+		const classList = className.split(' ');
+		classList.forEach(c => {
+		pane.classList.add(c);
+		});
+	}
+	this._overlayContainer.getContainerElement().appendChild(pane);
+
+	return pane;
+  }
+
+  /**
+   * Create a DomPortalHost into which the overlay content can be loaded.
+   * @param pane The DOM element to turn into a portal host.
+   * @returns A portal host for the given DOM element.
+   */
+  private _createPortalHost(pane: HTMLElement): DomPortalHost {
+	return new DomPortalHost(
+		pane, this._componentFactoryResolver, this._appRef, this._injector);
+  }
+
+  /**
+   * Creates an OverlayRef for an overlay in the given DOM element.
+   * @param pane DOM element for the overlay
+   * @param state
+   */
+  private _createOverlayRef(pane: HTMLElement, state: OverlayState):
+		OverlayRef {
+	const scrollStrategy = state.scrollStrategy || this.scrollStrategies.noop();
+	const portalHost = this._createPortalHost(pane);
+	return new OverlayRef(
+		portalHost, pane, state, scrollStrategy, this._ngZone);
+  }
+}