u must have winscp installed in ur pc and ssh client & server app on the n900 from extras u log in opening wi-fi from both devices and login on the winscp as a root and u go there to urs/share/themes/xxx/gtk-2.0/gtkrc then open the gtkrc file double click it and find the ######################
#
# Logical color definitions
#
######################
under it ull find the color sections u change the formats use this site to get the colors u want http://www.eligr.com/images/colors.gif