wxWidgets provides a global colour database (wxTheColourDatabase). Unfortunately the documentation doesn't show the colors for an easy selection. The following code extracts the definitions from wx/common/gdicmn.cpp and converts them into HTML:
sed -e 's;^\s*{wxT("\([^"]*\)"),\([^\}]*\)\},?;<span style="color: rgb(\2)">\1</span><br />;' gdicmn.cpp |grep '<span' > colors.html
AQUAMARINE
BLACK
BLUE
BLUE VIOLET
BROWN
CADET BLUE
CORAL
CORNFLOWER BLUE
CYAN
DARK GREY
// ?
DARK GREEN
DARK OLIVE GREEN
DARK ORCHID
DARK SLATE BLUE
DARK SLATE GREY
DARK TURQUOISE
DIM GREY
FIREBRICK
FOREST GREEN
GOLD
GOLDENROD
GREY
GREEN
GREEN YELLOW
INDIAN RED
KHAKI
LIGHT BLUE
LIGHT GREY
LIGHT STEEL BLUE
LIME GREEN
LIGHT MAGENTA
MAGENTA
MAROON
MEDIUM AQUAMARINE
MEDIUM GREY
MEDIUM BLUE
MEDIUM FOREST GREEN
MEDIUM GOLDENROD
MEDIUM ORCHID
MEDIUM SEA GREEN
MEDIUM SLATE BLUE
MEDIUM SPRING GREEN
MEDIUM TURQUOISE
MEDIUM VIOLET RED
MIDNIGHT BLUE
NAVY
ORANGE
ORANGE RED
ORCHID
PALE GREEN
PINK
PLUM
PURPLE
RED
SALMON
SEA GREEN
SIENNA
SKY BLUE
SLATE BLUE
SPRING GREEN
STEEL BLUE
TAN
THISTLE
TURQUOISE
VIOLET
VIOLET RED
WHEAT
WHITE
YELLOW
YELLOW GREEN