there is an issue with deleting and moving 2 points that overlap. Draw a simple polyline with the draw demo. Then move 2 consecutive points on top of each other. Save the new line. Enable editing again. If you then click on it, it will not be deleted, but a new one will be added underneath. You just cannot delete or move the point. If you move it, it creates a new one instead.
I'm using Chrome 26 on Mac.
This situation can happen often when editing GPS tracks, because sometimes a lot of points are very close to each other. A lot of my users are experiencing this problem.
Let me know if I need to create a detailed example.
I created a proof of concept with the example provided here. I made that the 2 interior point of the polyline have a duplicate. It is not possible to delete the point(s) by clicking on them. Tested with Chrome 26 and Safari.
I think what is happening is that you are clicking the middle point (which creates a new vertex). I think the easiest solution would be to provide the ability to turn off middle markers.
Would it be possible to have the middle markers have a lower z-index as the vertex points? I think the vertex points should have priority over the middle markers. I would like to retain the ability to have both vertex points and middle markers on at the same time.
This sounds reasonable to me. We should be able to use the zIndexOffset option of marker, using a negative value.