Inkscape mixes Fonts that have style other than that listed in one of its source file, i.e. "Demi", "ExtraLight", "Heavy", etc. are mixed with "Book", "Bold", etc. in the font selector and in documents in various ways.
DejaVu Sans Bold Oblique SVN has a fix specifying the style to be "Bold Oblique" which works with Inkscape, but ExtraLight will need a fix in Inkscape.
Inkscape mixes Fonts that have style other than that listed in one of its source file, i.e. "Demi", "ExtraLight", "Heavy", etc. are mixed with "Book", "Bold", etc. in the font selector and in documents in various ways.
DejaVu Sans Bold Oblique SVN has a fix specifying the style to be "Bold Oblique" which works with Inkscape, but ExtraLight will need a fix in Inkscape.