BTW, the choice of the gfx toolkit will be critical. Unfortunately, the C toolkits over there are turning very bad: GTK+ and the EFL do depend on harfbuzz for their font layout computation which is an *really* ugly c++ object-oriented brainfuckage (uglier that the glib SDK dependencies!). I did a C port of harfbuzz (drop-in replacement), but for basic text layout (roman style). Then to keep your GUI suckless, you should package a version of a toolkit to allow trashing harfbuzz, or avoid crazy SDK deps... This is unfortunately more work.
-- Sylvain