There are a bunch of applets in the panel that would be more visually
appealing if they supported transparency.  For example, while the
notification area looks okay with the panel using the system theme, setting
the panel to a color (with or without transparency) leaves the notification
area looking out of place as it is still using the system theme.  A bunch
of other applets common on the desktop suffer from the same issue: The
applications/actions menus, the clock, and the windows list are the obvious
ones.

How hard would it be to implement the following ideas.

1. Support 'invisible' backgrounds for these applets.   When using system
colors, this is effectively what happens.  Allowing the bgcolor to be
'invisible' would just allow the same effect with different colored
backgrounds.

2. Support handles with alpha-level transparency so that the buttons can
still be seen (for example the dimples) while the background color for the
bottom can be transparent, again allowing the button to blend into the
panel regardless of the colors behind it.

3. Where necessary, use the same font trick as with the desktop so that
fonts on wildly varying backgrounds stand out.

This would make the ability to change the panel look more visually
attractive, rather than the current situation where panels look 'awkward'
due to the presence of applets that are still using the system theme for
the background color.

I appreciate that this is all just 'eye candy' but I still think it's worth
a moments thought.  This would just mean changing the current defaults
rather than adding options and the new defaults would still give the same
effect as gnome gives now with the system theme, but would also give
excellent visual advantages with other panel setups too.