A new version of WebViewer has been released with a built in eraser tool as well as support for annotation grouping and leader line editing.
See the WebViewer changelog for all the details.
The annotation eraser tool allows you to delete annotations and erase parts of the path of freehand annotations.
PDF documents allow annotations to be grouped so that when one annotation is selected they all become selected and can be dragged around together. It also groups their note comments so that only one comment thread is shown for the entire group.
linkMeasurement annotation leader line editing
Using the setEnableLeaderLines function you can now edit the leader line length on distance annotations.
For all the changes see the WebViewer 5.2 changelog.