GtkScintilla::style_set_font

void style_set_font(int style, string font_name);

Set the font of some style.

// GtkScintillaStyle
define(  "SCINTILLA_STYLE_DEFAULT",   32 ); 
$scintilla->style_set_font(SCINTILLA_STYLE_DEFAULT, '-*-luxisans-medium-r-normal-*-18-*-*-*-*-*-*');