Fix for rounding error on drag-relation.

Fix for rounding error on drag-relation.

New service blocks have integer x/y coordinates, leading to mouseenter failing at the d.containsPoint() test when one of the mouse coordinates matched exactly with one of the edges of the service block.  To reproduce, create two new services (say varnish and node-app) and, without navigating away from the environment view, drag them to be diagonal relative to each other, then try to drag a relation from one to the other through the corner of the service node.  Correct behavior (this branch) should be for the drag line to snap to the two nearest connectors (as opposed to passing through the service without recognizing that it had entered).

https://code.launchpad.net/~makyo/juju-gui/bad-drag/+merge/130424

(do not edit description out of merge proposal)

[matthew.scott, 2012-10-18 20:24:55]

Please take a look.

[matthew.scott, 2012-10-19 14:33:37]

*** Submitted:

Fix for rounding error on drag-relation.

New service blocks have integer x/y coordinates, leading to mouseenter failing
at the d.containsPoint() test when one of the mouse coordinates matched exactly
with one of the edges of the service block.  To reproduce, create two new
services (say varnish and node-app) and, without navigating away from the
environment view, drag them to be diagonal relative to each other, then try to
drag a relation from one to the other through the corner of the service node. 
Correct behavior (this branch) should be for the drag line to snap to the two
nearest connectors (as opposed to passing through the service without
recognizing that it had entered).

R=
CC=
https://codereview.appspot.com/6741047