JAL-3446 from JAL-3253-applet Tree Canvas bug fix

- was possible to right-click off the node to get a NullPointer
exception.

diff --git a/src/jalview/gui/TreeCanvas.java b/src/jalview/gui/TreeCanvas.java
index 29ba52b..e59dfcc 100755 (executable)
--- a/src/jalview/gui/TreeCanvas.java
+++ b/src/jalview/gui/TreeCanvas.java
@@ -761,7 +761,9 @@ public class TreeCanvas extends JPanel implements MouseListener, Runnable,
      */
     if (e.isPopupTrigger())
     {
-      chooseSubtreeColour();
+      if (highlightNode != null) {
+        chooseSubtreeColour();
+      }
       e.consume(); // prevent mouseClicked happening
     }
   }