When an entry is more complex than a plain text - e.g. a formula, links, templates - clicking on switching from VE to wikitext editor will show Parsoid code briefly(sometimes it even stays for almost two min).
- In wikitext editor paste
<math>\ S[x(\tau)+\delta x(\tau)]-S[x(\tau)] =0</math>
- Click on Edit, and switch to VE. Add something to the entry and Save - the goal is to make VE to open next time by default.
- Open the entry again - it should open in VE. Then switch to wikitext editor.