Steps to reproduce:

1. Open an editor tab for a file with a format that parser of Outline drawer supports (eg. .md, .php or .js).
2. Open another editor tab for a file with a format that parser of Outline drawer does not supports (eg. .yml or .twig).
3. While the latter editor tab is focused, the text in the Outline drawer reads:

"There are no editors open that can provide outline information."

4. I do feel that this wording can be considered a bit misleading: in opposition what is currently means, the real fact that there is (at least – in the above scenario – one) editor tab open, which holds data that Outline parser can understand. Although, it's unfocused currently, indeed.
5. Therefore I suggest wording something similar like this:

The currently focused editor can not provide outline information.

As far as I searched, this message line occurs in code at /src/vs/workbench/contrib/outline/browser/outlinePanel.ts at line :459

• VSCode Version: 1.33.1
• OS Version: 10.13.6 (17G6030)

(Ps. issue #73213 was created first before the PR, sorry.)