OK I went fishing for the svg files and came across this: /fritzing-app/resources/parts/svg/do not change these svg files with anything but a text editor.txt
With the exeception of icon files, do on change resource svgs with vector graphics programs unless you are very very very very goddamn careful. For example, adobe illustrator does not recalculate stroke-width when loading SVGs when the units are not pixels. Secondarily, illustrator, inkscape, and the like tend to shove a lot of specialized extra crap into SVGs in order to facilitate later re-editing. Since many of the resource SVGs are used as generator templates, errors can proliferate beyond the single SVG that gets incorrectly changed; and the extra crap can muddy the templating process.
Hmmm I don't think the developers want you to edit the SVG's!