This may exist through some kind of theming tool, but I haven’t run across it so far.
When using significant numbers of attachments (images, PDF, etc.) the file view can get very cluttered. It would be nice if there was a toggle to limit the files shown in the explorer to *.md only.
An additional button in the top section next to New Note, New Folder, Sort order which toggles between an all files view and a .md only view similar to the edit/view toggle icon use on articles.