src/vs/workbench/browser/parts/editor/editorPart.ts/EditorPart/copyGroup
class EditorPart:	copyGroup(group: IEditorGroupView | GroupIdentifier, location: IEditorGroupView | GroupIdentifier, direction: GroupDirection): IEditorGroupView {
		const groupView = this.assertGroupView(group);
		const locationView = this.assertGroupView(location);

		const restoreFocus = this.shouldRestoreFocus(groupView.element);

		// Copy the group view
		const copiedGroupView = this.doAddGroup(locationView, direction, groupView);

		// Restore focus if we had it
		if (restoreFocus) {
			copiedGroupView.focus();
		}

		return copiedGroupView;
	}