Erroneous 3D box translation on saving.

[Martin Goik]

Problem: A 3D box containing text gets translated when saving and reopening an image. Steps to reproduce:

1. Create a 3D Box with vanishing points in infinity (parallel edges) for all 3 dimensions.
2. Put some text string "Test" inside the box moving it to topmost layer
3. Save the image as test.svg, see attachment. Everyting looks fine in Inkscape.
4. Close Inkscape.
5. Restart Inkscape and reopen test.svg

Inkscape now displays the text at its correct position. The 3D Box however appears being translated ways beneath the text and even outside the graphic's bounding box.

The attached report.zip contains:

test.svg: File being saved from Inkscape
inkscape.png: A Screenshot showing test.svg being reopened in Inkscape
imagemagic.png: A screenshot showing the very same file being viewed using the ImageMagic display application.

System Information: Ubuntu 16.04.2 64 bit, Inkscape 0.92.1 unknown

[Martin Goik (goik)]

Two further observations:

2. When displaying the 3D properties the vanishing point lines emerge from the original (correct) position rather then from the visible object

2. When opening a second graphics having a related problem simultaneously this one gets rendered correctly in Inkscape. Then closing the first and reopening it also renders it correctly.

[Martin Goik (goik)]

Adding package name (metadata)