This gtkWindow idea came to me yesterday after reading some code sent by Peter Clifton to the cairo-devel list and I consider it the best approach I could recently figure out. It is not that inconvenient. Indeed this is a lot useful since now I can see some rendering, and I can focus more on the task itself instead of boilerplate constraints.
If I work nice on the cairo world, I guess there wont be much problem when incorporating a future pango support for cairo-userfonts, do you agree?
My anxieties are twofold:
1) I think you're underestimating the amount of work which will be required to do the pango integration, since it will also involve all the stuff for text layout and mixing user fonts with normal fonts.
2) You can't use cairo functions for drawing to the Inkscape canvas, except in outline mode. It'll be a significant glitch in your (thus far excellent) progress when you need to start compositing with other content.
Richard.