Display of image attachments

[Craig Routledge <webstuff craigroutledge com>]

I was looking to re-enable the inline display of image attachments in the  
"complete message" view of a message window.  However, I'm a little  
confused about the message body widget.  I've examined the  
balsa-mime-widget* files but I'm having trouble tracing how a multipart  
message is assembled in the window.  Even gdb doesn't seem to make it very  
clear.

For example, a multipart MIME message with a text part followed by an image  
part has the following in its backtrace:

(heavily editied)
balsa_mime_widget_new
balsa_mime_widget_new
balsa_mime_widget_new_multipart
balsa_mime_widget_new
balsa_mime_widget_new
balsa_mime_widget_new_text

and yet balsa_mime_widget_image_resize_all is called, so it is processing  
the image part but not displaying it.

Where does Balsa decide to include or not display a part when showing  
"complete message"?  Where is the container for multiple parts that can be  
displayed (e.g. text/plain and a text signature as an attachment)?

Could someone familar with the code please give me a rough overview of the  
process?