bug#41376: Features request - Improving newsticker

[Nicola Manca]

Dear Emacs Devs,

While starting to use newsticker-tree as RSS reader, I found out some 
missing features that IMHO would greatly improve its usability:

- Groups cannot be sorted as the feeds (M-<up/down>)

- New feeds can be added by pressing 'a', but not removed. AFAIK there 
is no function call to do this job. It would be nice to have a 'd' 
keybinding to remove a feed (maybe with a confirmation dialog).

- It would be quite handy if the feed's displayed name would correspond 
to the label assigned, some feeds have an incredibly long name that 
doesn't fit the right window (if you keep it at a reasonably width).

- Import opml does not preserve the tree structure, new groups have to 
be created and populated.

- Focus does not follow the cursor, this is quite uncomfortable when you 
want to operate on a feed you have the cursor on, but the highlighted 
one is another.

- Feeds arrangement needs to be save continuously by pressing 's', this 
is total counter-intuitive and, even if I was aware of it, many times I 
did save and found out my feeds spread around, again.

- Even if i disabled the visualization of icons next to a feed name, 
those who were already downloaded remained there.

- Some operations are incredibly slow, marking 'old' a feed with ~100 
items takes several seconds.

These are the small usability issues I found so far. They may seems 
minor but in my experience are those small stuff may be quite relevant 
for new users.

Regards,
Nicola Manca