Show/hide labels for map clicks

MapEventListener, has special functionality: a small label text indicating info about clicked object, as a "Label". This is implemented in following way:

• If you click on an object, then it creates another map object: BalloonPopup with a text from metadata of the clicked object. This is why in samples we add special Metadata field value. You can use metadata value directly, or use object unique ID as metadata, and then use database to query details about clicked object.
• When user clicks new location on map, or object, then previous balloon is deleted, and new one is opened in new location

The BalloonPopup is added to a DataSource, which is linked to already existing Layer on map. We use same datasource what we use for other vector elements on map.

See Event Listener guide for sample code.