Import Inkscape SVG loses layer and sub-layer information

Reproduced with Inkscape 0.47 on OS X 10.5.8

workround:
1) after import, un-group only once
2) open XML Editor
3) in the nodes list select the layer that was active when importing the SVG file
4) in the main window un-group the now selected layer

Result: layers of the imported SVG file are now -as expected- on the same top level. In this example (self-import) they duplicate the existing layer structure including all sub-layers.

All (existing and imported) layers are listed and selectable in the 'Layers…' dialog.

Note: the new top-level layers loose the attribute 'inkscape:groupmode="layer"', whereas all of their sub-layers do keep it after importing and un-grouping.

Same thing happens to PDF and AI, so I don't think it needs an extra bug report. But I'm mentioning it here instead :)

> Same thing happens to PDF and AI, so I don't think it
> needs an extra bug report.

I don't quite agree ;) Importing SVG IMHO is a special case, because the layer structure in the imported Inkscape SVG file exists and seems obscured by the UI for layers (layers <-> groups).

Missing support of internal layer structure of PDF and AI files (Do PDF files really have a layer structure?) is IMHO a different issue and depends on an import filter capable of interpreting the content of the PDF as Inkscape layers or even reverse-engineering the AI proprietary format.

Yes, PDF files do have layer structure. There is nothing proprietary in PDF-compatible AI files

See also bug #227472 “[patch] improved SVG import” (comment #4):
«Import currently seems to work on the principle that the imported image should be a single object that the user can easily move about, resize, rotate, etc. That makes sense to me, and isn't really compatible with having the imported image spread over several layers. So the current behaviour (layers are converted to ordinary groups on import) seems like the best default behaviour. A "preserve layers" mode might be useful as a preference option, although I'm not sure where the new layers should go (on top of the existing layers? just above the current layer? as sublayers of the current layer?).»
<https://bugs.launchpad.net/inkscape/+bug/227472>

Setting importance to 'Wishlist': implement a "preserve layers" mode as import or preferences option.

I've found that if the SVG that you are importing has a top layer, the layers are preserved.

Start:
new.svg (importing into this file)
Icon Layer (select this layer before importing)

import.svg
Icon
> Final
> Dimensions

After:
Icon Layer
> Icon
> > Final
> > Dimensions

A bit cumbersome, but preserves layers without needing to do mess with grouping.