Comment 2 for bug 502075

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.