When constructing a GdkColor directly, you will need to use the system's color names, hex RGB triples or XcmsRGB values. Attempting to use other formats here will not result in an error message, because the structure itself recognises them, but equally they will not display, because the function doesn't recognise them at all.

The options when directly constructing colors in PHP-GTK are:

<?php
/* XcmsRGB values, expressed as three integers */
$cyan = &new GdkColor(0, 65535, 65535);

/* hex triples expressed as a single string */
$cyan = &new GdkColor('#00FFFF');

/* a color name expressed as a single string */
$cyan = &new GdkColor('cyan');
?>

Color names that are used on a given system are defined in a file named rgb.txt. The equivalent file is not available in human-readable form under win32, although utilised. Here is one of the better reference pages currently online detailing the standard color names used by window management systems.

See also: GtkStyle.