For longer operations a progress bar is something we should have, it's definitely useful. But if we show a progress bar then the busy indicator is redundant.

Further should we not duplicate the busy indicator on folder and account. The context of the folder is nice, on the other hand having a consistent place where the busy indicator shows up is a plus too. Plus for some operations we simply won't have a context other than the account/resource.

On a related note; the history/timeline could also be a place to visualize progress on an operation on top of the list. Perhaps as a way for for us to keep the hints fairly minimal normally, and if you must know there is still an interface that gives your more detailed insight (perhaps including downloadspeed etc at some point).

The plan is:

• No busy/error indicator on folder or account
• Single status text in status bar (perhaps with icon if useful)
• Progressbar next to status text for longer operations
• Progressbar on top of maillist (as maillist delegate so can be scrolled away from) for the special case of "I'm waiting for a new email and therefore I'm waiting until this becomes available.

This solution gives use in general very little visual noise. More detail information is available in the Log/Timeline view. Certainly errors and alike, and potentially progress on all ongoing operations (if we find that useful.).

In T6046#93056, @cmollekopf wrote:

The plan is:

• No busy/error indicator on folder or account
• Single status text in status bar (perhaps with icon if useful)
• Progressbar next to status text for longer operations
• Progressbar on top of maillist (as maillist delegate so can be scrolled away from) for the special case of "I'm waiting for a new email and therefore I'm waiting until this becomes available.
  
  This solution gives use in general very little visual noise. More detail information is available in the Log/Timeline view. Certainly errors and alike, and potentially progress on all ongoing operations (if we find that useful.).

While it reduces visual noise, it also moves the place of the feedback away from the action

True, but I think it works well in this case.

The locality is perhaps not only an advantage because at least in some cases the user doesn't explicitly trigger an action on the folder, it's more an implicit request by the system.
Therefore the user perhaps doesn't even understand the connection between action and reaction and therefore the locality perhaps isn't even useful.
Also, the constant placement is a benefit for finding the information if you're looking for it.
Further we end up in a situation where we either have to find a suitable place for all information, or we have to fallback to something like the account name, which seems like a bit of a workaround. Also, unless a single icon is expressive enough we end up with something additional anyways.

In any case, the new approach feels much nicer to me so far, let's see what others think once it's pushed.

I am happy to try.