Sorry Orion, the actual colour of the icon image is controlled by
<element id="Panel.CommandButtonOverride" bg="0,0,0,0" fg="193,152,103" />
and
<element id="CaptionBar.CommandButtonOverride" bg="0,0,0,0" fg="190,150,101" />
Don't forget that it will also change the colour of "DownloadIndicatorIcon" and "NotificationIcon" when they get displayed.
BTW, if you don't use the override, the fg attribute of
<element id="Panel.Header.Default" bg="42,42,38" fg="208,163,113" bdr="136,100,60" />
controls the colour.