PDF from PlantUML via Inkscape

plantuml -tsvg -pipe < input.pu | inkscape --pipe --export-area-drawing --export-text-to-path --export-type=pdf --export-filename=output.pdf

Coloured arrowheads

Found on Slashdot (didn’t note the link):

Create normal arrow.
Select the curve with the arrow point on it.
Ctrl+Alt+C or Path ▷ Stroke to Path.
Select the arrow tip in node selection mode and color it (both stroke and fill can be colored).
Thank you, drive through please.

UPDATE: This was fixed in the late 0.9-series and is no longer necessary in Inkscape 1.x.