• VSCode Version: 1.10.2
• OS Version: Ubuntu 14.04

Steps to Reproduce:

1. Open a Markdown file.
2. Open the preview (ctrl+shift+v).
3. Close the Markdown file tab (not the preview).
4. Scroll a few times in the preview tab.
5. Open any other file.
6. Go to the preview tab again. Notice that the scrollbar is reset to top.

My suggestion is that the scroll position of Markdown preview tab should follow its corresponding raw Markdown tab's only if the raw Markdown tab is present. If it is not present, the preview tab should preserve the last scroll position.