Failing to create an SVG-in-OT font using ttx/fonttools


I'm trying to create an SVG-in-OpenType font by adding an 'SVG '-table to an existing font, but the SVG glyph will not render in the final font.

This is my process:

1. I take an existing font and decompile it with ttx (Behdad's version)

2. I add an SVG table with a single svgDoc entry holding an SVG image.

3. I recompile the ttx (without errors) and test the font in Firefox (which supports SVG-in-OpenType).

Although ttx doesn't throw any errors, the SVG glyph doesn't show up — the original glyph is being shown.

My addition to the font looks like this:

<svgDoc endGlyphID="4" startGlyphID="4">
<!-- svg data -->

I've tried the following: