message: Switch to the new tab when moving a frame into new tab
diff: @@ -530,8 +530,8 @@ export class MainWebUi extends ThemeableElementBase implements keybindingmanager
  });
  newTerminal.addEventListener(EtTerminal.EVENT_EMBEDDED_VIEWER_POP_OUT, (ev: CustomEvent): void => {
  - this.openViewerTab(ev.detail.embeddedViewer, ev.detail.terminal.getFontAdjust());
  - this._switchToTab(ev.detail.embeddedViewer);
  + const viewerTab = this.openViewerTab(ev.detail.embeddedViewer, ev.detail.terminal.getFontAdjust());
  + this._switchToTab(viewerTab);
  ev.detail.terminal.deleteEmbeddedViewer(ev.detail.embeddedViewer);
  });
  @@ -561,7 +561,7 @@ export class MainWebUi extends ThemeableElementBase implements keybindingmanager
  return newTerminal;
  }
  - openViewerTab(embeddedViewer: EmbeddedViewer, fontAdjust: number): void {
  + openViewerTab(embeddedViewer: EmbeddedViewer, fontAdjust: number): EtViewerTab {
  const viewerElement = embeddedViewer.getViewerElement();
  const viewerTab = <EtViewerTab> document.createElement(EtViewerTab.TAG_NAME);
  viewerTab.setFontAdjust(fontAdjust);
  @@ -575,6 +575,7 @@ export class MainWebUi extends ThemeableElementBase implements keybindingmanager
  viewerTab.setViewerElement(viewerElement);
  this._updateTabTitle(viewerTab);
  + return viewerTab;
  }
  private _openViewerTab(tabWidget: TabWidget, viewerElement: ViewerElement): void {
  