So… It appears Inkscape decided to switch from 90dpi to 96dpi (to follow recommendations they claim…). And when you open an 'old' SVG in new inkscape, it enforces some kind of conversion.
Problem is, I tried all three choices, and none work 'off hands' for us (either generation of PNG at build time crashes, or we get black or shattered icons in UI).
Did not dig that much more, but I suspect that since 90 to 96 DPI is not a simple nice round conversion, we end up with fractions of our pixels, and our icon-generation tools expect some precise, integer pixel size of icons.
In other words, it would appear that we cannot keep our current fixed-pixel size of icons (at least, not without some manual conversion of the whole SVG).
There are two issues here actually:
- Compatibility: Which ever solution we choose, we'll have to forbid either older inkscape, or new ones. It is clearly impossible to support/allow usage of both.
- Fixing the issue itself: I see at least three options, there may be more…
- Ignore new inkscape, and keep using older one (will be a bit annoying to keep old inkscape at hands in linux distros though, and this is not a good future-proof solution…).
- Accept change of our icons size (which seems necessary if we want to use some new converted SVG off-hands).
- Manually tweak bloody SVG file after conversion to 96dpi, to put it back in shape that we can use to generate our current icon sizes.