Problems with image import sizes

There seem to be two issues here:

1) When images are imported, they are given a size in mm rather than sp. For consistency in scores with different scaling factors, a universal pixel-per-sp is needed for importing.
2) Ticking/unticking ‘Size in stave space units’ in the inspector results in the image changing size, and the new displayed size being incorrect until refreshed by clicking off and on the image again. I get the impression the image is supposed to stay the same size and only the displayed measurement units are meant to change?

See:
https://musescore.org/en/node/17427 (from 2012)
https://musescore.org/en/node/265973

The attached files are a small graphic (treble clef, staff lines, and time signature) exported with two different scaling factors. Exported with 180dpi as this seems to be built in as a constant for preserving size.

To see the problem, I suggest the following reproduction methods:

1)
Drag ‘export-180dpi-1.764mmsp.png’ into MuseScore (with the default template open). The size will be correct (drag it to the treble clef to verify). Unticking ‘Size in stave space units’ in Inspector, however, will resize the image.
2)
Change the scaling factor for the MuseScore document, for example to 1.234mm, then drag ‘export-180dpi-1.764mmsp.png’ back in. It will now be the wrong size.
3)
Drag ‘export-180dpi-1mmsp.png’ into MuseScore. It will almost certainly be the wrong size. Untick ‘Size in stave space units’ in Inspector, then click on ‘100.0%’ and press Enter, then retick ‘Size in stave space units’. This will now be the right size regardless of the sp scaling factor.