Open editors in the active editor group if now viewcolumn is specified

[bpasero]

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.

[jrieken]

However, it looks like the view column is always undefined for diff editors at least.

Yes, that how it is defined because otherwise both editors will have the same view column which is a little bogus. The viewColumn is just a weak hint, also because it will be undefined for other editors, embedded, output etc. Unsure what to do here, unsure if two editors should have the same view column...

[bpasero]

Interestingly this would be not much of an issue if the viewColumn by default would not be set to ViewColumn.ONE from the extension host. If undefined, the workbench is always picking the column that is currently active. But I guess that would be a breaking change, at least from the docs:

[jrieken]

Yeah, I think we can always tweak that. And more than you want that: #27409 I am just not yet sure about the implementations...

[bpasero]

@jrieken yeah it looks like #27408 is the git diff issue I was seeing.

[bpasero]

I pushed a change to open an editor in the currently active editor group if no group is provided. I think this plays much better with the new grid system. As for other impact the grid should have on extensions API I have opened #51001