Last modified: 2014-01-08 18:38:19 UTC
Edit an existing post. When you start typing, you'll see one or both of these issues (both reported on Chrome): the bottom of the textbox flutters up and down by a pixel as you type, and/or the save/cancel/preview buttons flutter up and down as you type.
The WMF core features team tracks this bug on Mingle card https://mingle.corp.wikimedia.org/projects/flow/cards/571, but people from the community are welcome to contribute here and in Gerrit.
I'm not seeing this issue anymore.