Inkscape's ebuild specifies minimal required version of gtkmm as 2.4, but in fact gtkmm >= 2.10.0 required: checking for INKSCAPE... configure: error: Package requirements (gdkmm-2.4 glibmm-2.4 gtkmm-2.4 >= 2.10.0 gtk+-2.0 libxml-2.0 >= 2.6.11 libxslt >= 1.0.15 cairo sigc++-2.0 >= 2.0.12 gtkspell-2.0 gthread-2.0 >= 2.0 libpng >= 1.2) were not met: Requested 'gtkmm-2.4 >= 2.10.0' but version of gtkmm is 2.8.3 Reproducible: Always
Fixed in media-gfx/inkscape-0.46-r2. Thanks for the report.