Comment 6 for bug 171331

@Alvin - np

Question/Notes wrt new feature:

- Better support to identify mass center symbol with object?
Maybe the inserted cross could use a custom id composed of a name describing its purpose, and the id of the path it originally applied to? 'MassCenter_path1234' for example would allow to find it by id of the original path (via 'Edit > Find').

- Better support for snapping?
Currently there is no node at the actual location of the mass center - it is at the intersection of two line segments (intersection is a costly snap target). I assume that one use case of the visualization of the mass center would be to be able to position the path such that the mass center aligns (snaps) with other elements on the canvas (or guides, or grid lines). This does not work if what ought to be snapping is actually an intersection of two paths (at least not in trunk, when dragging a group which contains the original path and the cross).
Would it make sense to either insert a node in the center of one of the two lines, or draw them differently [1], so that there is a node present which can be used for snapping while dragging a selection or group of the mass center and the original path?

[1] e.g. draw two 90° angled lines (3 nodes each) instead of 2 crossing lines (2 nodes each)