The current default Terra Theme font is "Verdana 11". While this is a nice-looking font, it is not available (by default) on platforms other than Windows, and it does not support a wide range of the Unicode character set (typically not much outside the Latin-1 range). This is a problem for applications needing to routinely handle Japanese, Korean, Chinese, etc. characters in the GUI.
The proposal would be to change the default theme font to either "DIALOG 12" or maybe "SANS_SERIF 12" in order to take advantage of the increased character set coverage in these "logical" fonts.
Since this is a big visual change, it is not clear if it should go into 2.0.5 or not.