Comment 16 for bug 459811

> Unless it's obvious that the symptoms are the same
Digging further into this:

A) the bug already exists in Inkscape 0.46 (and 0.46+devel < r22019?):

start inkscape, set arc controls to
| ui controls bar start/end values: 45 / 135
quit inkscape
| preferences.xml start/end values: 0.78539816 / 2.3561945
restart inkscape, select ellipse tool
| ui controls bar start/end values: 0.785 / 2.356
quit inkscape
| preferences.xml start/end values: 0.013707784 / 0.041123352

i.e. start and end values (x) are written as (2pi/x) to the prefs but read as "x" in degree. Once the values have been changed from 0, they get smaller every time Inkscape 0.46 (0.46+devel < r22019?) is started, until they reach so small values that the resulting arc/segment is no longer visible.

B) the bug is not fixed in Inkscape 0.47(pre) but hidden:

start inkscape, set arc controls to
| ui controls bar start/end values: 45 / 135
quit inkscape
| preferences.xml arcstart/arcend: 0.78539815999999985 / 2.3561945
| preferences.xml start/end values: 0 / 0
restart inkscape, select ellipse tool
| ui controls bar start/end values: 0 / 0
quit inkscape
| preferences.xml arcstart/arcend: 0 / 0
| preferences.xml start/end values: 0 / 0

The controls bar values for start and end are written as (2pi/x) values into the group "shapes" (instead of the eventcontext "arc"). However they are still read from within the eventcontext "arc" when activating the arc tool.

Some (?) routine however still writes start/end values to the eventcontext "arc" and then these values are read as "x" in degrees (still wrong!) and used as default for start/end of new arcs/ellipses. There is no apparent way in the GUI to change these start/end default.

tested with these steps:
quit inkscape, mnually edit preferences.xml
| preferences.xml arcstart/arcend: 0.5 / 1.0
| preferences.xml start/end values: 0.5 / 1.0
restart inkscape, select ellipse tool
| ui controls bar start/end values: 0.5 / 1.0
and draw an ellipse - you only get an arc:
| ui controls bar start/end values: 28.648 / 57.296
quit inkscape
| preferences.xml arcstart/arcend: 0.5 / 1.0
| preferences.xml start/end values: 0.5 / 1.0
restart inkscape, select ellipse tool
| ui controls bar start/end values: 0.5 / 1.0
and draw an ellipse - you only get an arc:
| ui controls bar start/end values: 28.648 / 57.296
change the arc to a whole ellipse with the controls bar button
| ui controls bar start/end values: 0 / 0
quit inkscape
| preferences.xml arcstart/arcend: 0 / 0
| preferences.xml start/end values: 0.5 / 1.0
restart inkscape, select ellipse tool
| ui controls bar start/end values: 0.5 / 1.0
and draw an ellipse - you only get an arc:
| ui controls bar start/end values: 28.648 / 57.296
quit inkscape
| preferences.xml arcstart/arcend: 0.5 / 1.0
| preferences.xml start/end values: 0.5 / 1.0