From 40eca0b26f0e394be8a6db601effff067dea0a71 Mon Sep 17 00:00:00 2001
From: zepumph <michael.kauzmann@colorado.edu>
Date: Tue, 26 Jan 2021 17:01:30 -0900
Subject: [PATCH] only add/remove if applicable, support weird focus cases,
 https://github.com/phetsims/scenery/issues/1147

---
 js/listeners/PressListener.js | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/js/listeners/PressListener.js b/js/listeners/PressListener.js
index 88a97e562..bcc2da117 100644
--- a/js/listeners/PressListener.js
+++ b/js/listeners/PressListener.js
@@ -894,7 +894,9 @@ class PressListener {
       'cannot focus node with zero or multiple accessible displays attached' );
     //
     this.display = accessibleDisplays[ 0 ];
-    this.display.focusHighlightsVisibleProperty.link( this.boundInvalidateOverListener );
+    if ( !this.display.focusHighlightsVisibleProperty.hasListener( this.boundInvalidateOverListener ) ) {
+      this.display.focusHighlightsVisibleProperty.link( this.boundInvalidateOverListener );
+    }
 
     // On focus, button should look 'over'.
     this.isFocusedProperty.value = true;
@@ -907,7 +909,9 @@ class PressListener {
    */
   blur() {
     if ( this.display ) {
-      this.display.focusHighlightsVisibleProperty.unlink( this.boundInvalidateOverListener );
+      if ( this.display.focusHighlightsVisibleProperty.hasListener( this.boundInvalidateOverListener ) ) {
+        this.display.focusHighlightsVisibleProperty.unlink( this.boundInvalidateOverListener );
+      }
       this.display = null;
     }