just a little comment on the flow viewport.
it would be cool to have a little nodes-navigation-view in the flow-viewport corner (like in combustion, shake, etc.) instead scrollbars. its much faster & more comfortable to navigate through the little interactive navigation-window than to move/ mess around with scrollbars. and also the gui looks much better without ugly windows-scrollbars 
maybe this could be something for 4.1
thanks for reading