Add when context: isLastGroup / isFirstGroup / editorGroupIndex

[joshfrench]

• VSCode Version: 1.10.2
• OS Version: 10.11.6

I've remapped a shortcut to View: Focus Next Group. This command will open an additional group if I'm on the last group and have fewer than 3 groups currently open.

It would be great to have a when clause to prevent this. A clause like editor.isLastGroup (or perhaps a combination of editor.openGroupCount and editor.currentGroupIndex) would allow me to prevent extraneous group opening. A similar check for editor.isFirstGroup would let me re-use the same shortcut to jump back and forth between the first group and the sidebar.

Thanks for your consideration!

[bpasero]

PR welcome.

[jaydenwindle]

+1 for this. Just switched from vim to vscode recently. Being able to jump back and forth between the sidebar and the first editor group in a similar manner to vim + NERDTree would be great.

I'd be happy to take a stab at a PR. @bpasero any advice for implementing this feature? Good places to start, people I should chat with about it, resources on how when clauses are implemented, etc. would all be helpful :)

[bpasero]

@jaydenwindle maybe look how we update the context for diff editor being active or not: https://github.com/Microsoft/vscode/blob/master/src/vs/workbench/browser/parts/editor/editorPart.ts#L662