Adding documentation and PressListener more comprehensive disposal, see

#131 and phetsims/sun#372

js/listeners/DragListener.js

@@ -60,6 +60,11 @@
  *     }
  *   } )
  *
+ * It's completely fine to use one DragListener with multiple objects, however this isn't done as much since specifying
+ * locationProperty only works with ONE model position Property (so if things are backed by the same Property it would
+ * be fine). Doing things based on modelPoint/modelDelta/etc. should be completely fine using one listener with
+ * multiple nodes. The typical pattern IS creating one DragListener per draggable view Node.
+ *
  * @author Jonathan Olson <[email protected]>
  */
 
@@ -96,7 +101,9 @@ define( require => {
     options = merge( {
 
       // {Property.<Vector2>|null} - If provided, it will be synchronized with the drag location in the model coordinate
-      // frame (applying any provided transforms as needed).
+      // frame (applying any provided transforms as needed). Typically, DURING a drag this Property should not be
+      // modified externally (as the next drag event will probably undo the change), but it's completely fine to modify
+      // this Property at any other time.
       locationProperty: null,
 
       // {Function|null} - Called as start( event: {Event}, listener: {DragListener} ) when the drag is started.

js/listeners/FireListener.js

@@ -1,7 +1,8 @@
 // Copyright 2017-2019, University of Colorado Boulder
 
 /**
- * A listener for common button usage, providing the fire() method/callback and helpful properties.
+ * A listener for common button usage, providing the fire() method/callback and helpful properties. NOTE that it doesn't
+ * need to be an actual button (or look like a button), this is useful whenever that type of "fire" behavior is helpful.
  *
  * For example usage, see scenery/examples/input.html. Usually you can just pass a fire callback and things work.
  *

js/listeners/PressListener.js

@@ -810,9 +810,14 @@ define( require => {
       }
       !this.isHoveringProperty.isDisposed && this.isHoveringProperty.unlink( this._isHighlightedListener );
 
+      this.overPointers.dispose();
+      this.isPressedProperty.dispose();
+      this.isOverProperty.dispose();
+      this.isHoveringProperty.dispose();
+      this.isHighlightedProperty.dispose();
+      this.isFocusedProperty.dispose();
       this.a11yClickingProperty.dispose();
       this.looksPressedProperty.dispose();
-
       this._pressAction.dispose();
       this._releaseAction.dispose();