Portable desktop version 1.0.231 on Windows 10.
When editing very large documents, with the editor and viewer open a single edit in the editor window causes it to auto scroll to the bottom of the pane, or a random place within the window. The cursor remains in the correct place in the document, but the only way to get back to where you were editing is to type something which causes the process to repeat.
I don’t know if this is a recent bug, but it makes editing almost impossible.