Steps to reproduce:
- Enable NWE on https://de.wikipedia.beta.wmflabs.org
- Go to https://de.wikipedia.beta.wmflabs.org/wiki/Benutzer_Diskussion:PerfektesChaos#Modul:DateTime
- Click "Quelltext bearbeiten" for that section.
Expected result: The source code is visible from start.
Actual result: While loading the editor, the page jumps up (about 1.5 screens), when the source code editor is visible, the content is scrolled up.
Just for the case this is a browser issue: Firefox 49.0.2 on Linux