That graphic *is* vertically aligned properly.  It doesn't look 
aligned compared to the other graphics because the fire portion 
extends above the letter portion.  But this is simply a limitation of 
that icon, not a bug.

That graphic is also 18px wide (instead of 16px) so it was being 
cutoff.  I have fixed this particular issue.

Changes have been made in Git for this ticket:

Bug #10601: CSS tweak

  2 files changed, 2 insertions(+), 0 deletions(-)
http://git.horde.org/horde-git/-/commit/5478cb65e86aed83cb901c15da4bc42f12e006cb

IMHO, I lot of themes are really outdated and looks horrible after all 
these years. Like Large Contrast theme or Postnuke. Large portion of 
them changes nothing in Dynamic View, e.i. same icons, same fonts, 
same sidebar color in IMP. It's just header and background color of 
the message list which changes. I would suggest lose such themes 
entirely.

For others, Horde could follow some backward compatibility policy. All 
major open source projects have one for themes.

This underscores an issue I have brought up before: it is pretty much 
impossible for us (as devs) to support any theme other than the 
default.  I personally can't go through and test every theme when I 
make a CSS change outside of the default theme.

Would love to see all themes other than the default (and silver) be 
removed from our distributions and then have some method of 
packaging/installing other themes.

No, not at the moment. Just wanted to create a ticket because I've 
actually noticed this since early IMP5 alpha but always got lost 
between more important work.

Patch?

Spam icon on the spam button in dynamic view is not vertically aligned 
properly. It is couple of pixels lower than the rest of the icon on 
Reply/Forward/Delete buttons.

This is under Blue and White theme. Silver Surfer looks fine.