After upgrade of media-libs/fontconfig to 2.13.0 gitk fails with the following message. Downgrade to media-libs/fontconfig-2.12.6 helped. Error in startup script: bad screen distance "4.5" while executing "$canv conf -scrollregion [list 0 0 $canvxmax $ymax]" (procedure "setcanvscroll" line 6) invoked from within "setcanvscroll" (procedure "initlayout" line 17) invoked from within "initlayout" (procedure "getcommits" line 4) invoked from within "getcommits {}" (file "/usr/bin/gitk" line 12613)
Problem gone with media-libs/fontconfig-2.13.0-r1