If you write article with the smileys used by tinyMCE, the smileys are in .gif format.
If you want to create a PDF, you get the error: gif not supported.
This of course is not 'quality' that fits in joomla.

Therefore I have 2 solutions:
1 - Change all the images from .gif to .png in the joomla package (Lots of work and propably ruining the images)
2 - Create a simple plugin which is used creating a pdf and let it convert the non-supported formats to png (Or something like that)
I do not know if things like this are planned or if there are ideas. I did not found an article about solving this issue.
Regards,
Nicholai