src/vs/workbench/browser/parts/editor/editorGroupView.ts/EditorGroupView/doMoveEditorInsideGroup
class EditorGroupView:	private doMoveEditorInsideGroup(candidate: EditorInput, options?: IEditorOpenOptions): void {
		const moveToIndex = options ? options.index : undefined;
		if (typeof moveToIndex !== 'number') {
			return; // do nothing if we move into same group without index
		}

		const currentIndex = this.model.indexOf(candidate);
		if (currentIndex === -1 || currentIndex === moveToIndex) {
			return; // do nothing if editor unknown in model or is already at the given index
		}

		// Update model and make sure to continue to use the editor we get from
		// the model. It is possible that the editor was already opened and we
		// want to ensure that we use the existing instance in that case.
		const editor = this.model.getEditorByIndex(currentIndex);
		if (!editor) {
			return;
		}

		// Update model
		this.model.moveEditor(editor, moveToIndex);
		this.model.pin(editor);

		// Forward to title area
		this.titleAreaControl.moveEditor(editor, currentIndex, moveToIndex);
		this.titleAreaControl.pinEditor(editor);
	}