What 12 hex digits color codes in xfce terminal configuration means?

Question

Recently I set up my XFCE terminal to use the perfect palette of Solarized using this prepared config.

All works fine (although midnight commander colors make me cry now) but one thing is really curious to me:

Why do color codes in xfce terminal settings contain 12 hex digits rather than 6? Like these one:

ColorPalette8=#d3d3d7d7cfcf

What does it mean? And how is it related to color codes specified on official page

Answer 1

GTK uses 16 bits per colour channel, i.e. 4 hex digits. A colour value for GTK can be encoded as #rgb, #rrggbb or #rrrrggggbbbb.