The original bug report was asking about text figures and lining figures. I've attached a PDF demonstrating the difference between these in the Linux Libertine font. The Ubuntu font is missing text figures. The Ubuntu font provides lining figures by default.
Specifically, the Ubuntu font needs to have text (old-style) figures added to it as well as the associated 'onum' OpenType feature. In addition an 'lnum' OpenType feature should be added so the lining figures can be addressed as such.
This bug hasn't been fixed yet.
The original bug report was asking about text figures and lining figures. I've attached a PDF demonstrating the difference between these in the Linux Libertine font. The Ubuntu font is missing text figures. The Ubuntu font provides lining figures by default.
Specifically, the Ubuntu font needs to have text (old-style) figures added to it as well as the associated 'onum' OpenType feature. In addition an 'lnum' OpenType feature should be added so the lining figures can be addressed as such.