Steps to Reproduce:

1. open a diff editor (from git) in the second or third view column
2. trigger the editor title action "Open File"
3. 🐛 the file opens in the first view column

I think the Git extension is doing the right thing for this command by setting the view column to be the one of the active editor, which in this case is the diff editor. However, it looks like the view column is always undefined for diff editors at least.

Tracing this down the stack, it looks like MainThreadDocumentsAndEditors#_onDelta is called with the left hand side of the diff editor as well as the right hand side (both instance of CodeEditor). As such, the method _findEditorPosition will not function properly because it compares the CodeEditor to the DiffEditorWidget which is opened.