Changing synapse size in skeleton view resets Neuroglancer view

[hubbardp]

To reproduce:
Do a "Find Neurons" query.
Click the Neuroglancer tab so the Neuroglancer view and skeleton view are appearing side by side.
Click on the body ID in the skeleton view, choose "Synapse Selection" then "Show All".
Make some changes in the Neuroglancer view: e.g., switch to show just the 3D panel and zoom in.
In the skeleton view, drag the "Synapse Size" slider
Expected: the synapse balls get larger in the skeleton view and nothing else changes
Observed: the synapse balls get larger in the skeleton view and the Neuroglancer view resets (e.g., instead of one 3D view zoomed in it shows a 3D view and a grayscale view zoomed out), and also the synapses flash on and off in the Neuroglancer view.

In the Clio code, we sometimes had a similar problem, and a solution was for the UI control callback code (e.g., the code to respond to the slider change in the skeleton view) to call actions.syncViewer();. That call invokes the case C.SYNC_VIEWER code here:
https://github.com/clio-janelia/clio_website/blob/master/src/reducers/viewer.js
Perhaps similar code needs to be added to neuPrintExplorer?