A small visual flaw (Priority: Low) related to self-explanation during operation when moving an item (folder or conversation).

When moving an item from a subfolder to the root of the root tree, it is hardly clear that this is possible at all.

You have to move the folder very precisely at the left edge of the root tree, otherwise the item may end up back in a subfolder or the move process may be aborted.

What I miss here, is the underline on root level when the user hovers the item on the correct level, like the second image.

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