Comment 5 for bug 903819

There are some subtle uses of color in the indicator icons:

 * messaging turns blue (and even had full colored icons briefly last cycle)
 * power cog (indicator-sesision) turns red when there's a problem in online accounts
 * sound turns dark when muted

Right now, this is handled by different icon names for the diffeterent states. For example, indicator-messages-new is a blue version of indicator-messages. I don't know if that can be easily replicated with symbolic icons. At the simplest, we'd need a way to specify the white color (maybe indirectly through widget state or so) when giving GtkImage an icon name.