1.3.19 (484) OS X 10.8.3
I think there may be an issue with constraining in this build. It seems to me that previously if I wanted to constrain a node to horizontal or vertical I could hold Shift (or maybe Option) and double-click on one of the control points which would constrain it.
It isn’t working that way now.
[edit] In fact I just discovered that constrain also doesn’t work when moving an object horizontally or vertically in the cell with the mouse and holding either the Shift or Option key.
[2nd edit] I just opened a file using Build 477 and tried it in that version. It works as I expected it to. So Build 484 definitely has a problem.