Markdown file preview on side, cannot find currently opened but unfocused source tab

[GehDoc]

• VSCode Version: 1.39.1
• OS Version: Fedora 30

Steps to Reproduce:

1. Open a markdown file
2. Open the Mardown preview on the side (Ctrl+k v).
   This opens a Markdow preview tab, in a new tabs group at the right of the window.
3. Give the focus to the left tabs group, by clicking inside the markdow file (source)
4. Open another file (Ctrl+o).
   This opens a new tab in the left tabs group.
5. Double-click on a line of text in the Markdown preview

This opens a new tab, in the right tabs group, to show the Markdow source.
It should have focused the existing tab, in the left tabs group.

Does this issue occur when all extensions are disabled?: Yes