[cairo] RenderBadGlyphSet (invalid GlyphSet parameter)

[Simon Burton]

I am using the cairo xlib surface, and I got this error on
one of the X servers we run:

'RenderBadGlyphSet (invalid GlyphSet parameter)'.
 (Details: serial 339 error_code 171 request_code 151 minor_code 20)

Has anyone seen this error before ? I also use gtk so I suppose it could
be a gtk problem. Or maybe I am confusing my cairo contexts.

thanks,

Simon.