Gwibbly, another theme for Gwibber
To install the new gwibber theme:
1. Download the new theme from google code
2. Decompress it to ~/.local/share/gwibber/ui/themes/
You should end up with folders names gwibbly-* with a few files inside it.
Make that path if it not present
3. In Gwibber, open Preferences (Gwibber->Preferences or Ctrl+P).
Pull down the theme chooser and choose ‘gwibbly’, or 'gwibbly-dark' etc.
4. On my system, it took Gwibber a few seconds to apply the new theme.
Be patient, and things should shape up.