Comment 5 for bug 1118663

this is an excellent addition to the existing hpgl code, thanks for doing this!

I particularly like the extensive tooltips, which are not very common in these Python extensions. Also the response to the case where pySerial is not installed is very graceful, no unexpected crash. (Personally, I wouldn't make pySerial part of the Inkscape package, users should be able to do this by themselves.)

The only concerns I have are about compatibility.
- For example, I think the default orientation angle would have to be 0, not -90, to be compatible with current code.
- the units of the offset at the origin are now mm instead of pixels.
- I believe the direction of movement in response to the origin offset is now the reverse of the original code
- the absolute coordinates of the original drawing appear to have been converted to relative coordinates by calculating the outline of the drawing.

Since I am not an actual user of this extension, I don't know if these changes are desirable or not, perhaps some feedback could be obtained from others, for example on the Inkscape users list.