Center of rotation on a horizontal/vertical line is inaccessible

[Cojnel]

When a horizontal or vertical line is selected,
it's transform handles are to close together,
they cover the middle handles on the short side
and the center of rotation.

1. draw a horizontal line (2 nodes is enough)
2. pick the selection tool
3. select the line
4. click on it once to show the rotation/skew handles
5. the center of rotation is inaccesible, because
the skew handles in the middle of the line are
positioned one above the other with
the center of rotation under them.

One possible solution:
The transform handles and the center of rotation are 14x14px,
if the corner and middle handles were positioned 14px apart,
then the scale and skew handles on the shortside of a
horizontal or vertical line and the center of rotation would
become accessible.

Another solution:
The same way as when two horizontal or vertical nodes
are selected, the unusable transform handles
(corner or long side scale handles and all four skew handles)
are hidden until the line is rotated.

6. pick the node editing tool
7. turn on "Show Transform Handles"
8. select 2 nodes on a horizontal line,
the middle handles on the long side and
the corner scale handles are hidden,
only the left and right scale handles are shown,
because that's the only direction a horizontal line can be scaled.
9. click on one of the nodes once, the skew handles are hidden,
only the rotation handles and the center of rotation is shown,
because that's the only way a horizontal or line can be manipulated.
10. rotate the two nodes slightly, as soon as the nodes aren't horizontal anymore
then the middle skew handles are shown, and depending on zoom level when
there is enough room for the skew handles on the short side of the line they are shown.

Tested with:
v0.48.4 r9939
and
r12852 on linux mint 15 cinnamon 32bit

[su_v (suv-lp)]

<opinion>

> Another solution:
> The same way as when two horizontal or vertical nodes
> are selected, the unusable transform handles
> (corner or long side scale handles and all four skew handles)
> are hidden until the line is rotated.
>
> 6. pick the node editing tool
> 7. turn on "Show Transform Handles"
> 8. select 2 nodes on a horizontal line,
> (…)

Related:
- Bug #590260 “[Node tool] Skew transformation handles missing for x- or y-aligned nodes”
  <https://bugs.launchpad.net/inkscape/+bug/590260>

Personally, I'm not really satisfied with such a solution: simply omitting transformation handles removes functionality. For the node tool, this for example negatively affects multi-path node-editing, where it is not unreasonable (nor impossible) to have a selection of multiple nodes which are aligned vertically or horizontally and which one needs to skew.
</opinion>

[su_v (suv-lp)]

Reproduced with Inkscape 0.48.4, 0.48.x r10006 and 0.48+devel r12852 on OS X 10.7.5.

[Duarte Ramos (duarte-framos)]

I also stumbled across this problem under 0.91 both under Widows XP and Windows 10, on perfectly vertical or horizontal lines one cannot change rotation pivot without accidentally scaling or skewing the path.
Unfortunately that also revealed another bug I reported yesterday at https://bugs.launchpad.net/inkscape/+bug/1514132 that skeweing a strokeless vertical or horizontal line cause inkscape to crash.

Workaround I found for now is to not draw vertical or horizontal lines, change the pivot first, then align nodes to make them vertical or horizontal and only then can I place the pivot where desired .