I'm implementing a mapping application with OpenLayers 3.

When there are too many overlays on the map (say you had to add too many location pins - see picture below), certain parts of the viewport have little or no space that will receive the mouse wheel events (i.e the overlay pins do not propagate the wheel events to the map) and the user thinks that his/her interaction is blocked. How can I prevent this?

Simply put: I put a simple image as an overlay on a map and the mouse wheel event on that image is not propagated to the map, therefore the interaction ol.interaction.MouseWheelZoom is not triggered.

I'm implementing a mapping application with OpenLayers 3.

When there are too many overlays on the map (say you had to add too many location pins - see picture below), certain parts of the view-port have little or no space that will receive the mouse wheel events (i.e the overlay pins do not propagate the wheel events to the map) and the user thinks that his/her interaction is blocked. 

How can I prevent this?

Simply put: I put a simple image as an overlay on a map and the mouse wheel event on that image is not propagated to the map, therefore the interaction ol.interaction.MouseWheelZoom is not triggered.