Can't add multiple variables when doing a pivot

I just started using this GUI, and it's pretty awesome! Thanks :)

**Describe the bug**
On the demo video, we can see that it's possible to have multiple values in the index, columns or values fields when doing a pivot.
https://www.youtube.com/watch?v=NKXdolMxW2Y#t=2m30s
However, now it seems this is not possible with the current interface.
Is that normal? It would be really useful to be able to create multi-index, multi-columns tables.
Maybe I'm missing something?

**Environment**
OS: Ubuntu 20.04
Python: 3.8.10
IDE: None

**Package versions**
```
ipython==8.12.2
pandasgui==0.2.14
plotly==5.14.1
PyQt5==5.15.9
PyQt5-Qt5==5.15.2
PyQt5-sip==12.12.1
PyQtWebEngine==5.15.6
PyQtWebEngine-Qt5==5.15.2
```