I searched with "update wordpress theme", "upgrade theme", "manually update theme", etc. and all I found were instructions on how to upload a new version of a style provided by the vendor/developer.
I am using a WP2.9 theme which will likely never see a WP3.x compatible version from the developer. I am not willing to scrap the theme and switch either. Is there a document that explains the changes from WP2.9 themes to WP3.3 themes?
I am reasonably conversant at HTML/CSS/PHP, but there doesn't seem to be a master list anywhere of style/code changes other than trawling through 500 pages of Release Notes.
Thanks in advance!