From 634afceda19c45e6d9790bfc23294a647b237fbc Mon Sep 17 00:00:00 2001
From: gmungoc <g.m.carstairs@dundee.ac.uk>
Date: Thu, 22 Mar 2018 16:14:03 +0000
Subject: [PATCH] JAL-914 singleton HelpBroker to avoid multiple help windows

---
 src/jalview/gui/Help.java |   59 +++++++++++++++++++++++++--------------------
 1 file changed, 33 insertions(+), 26 deletions(-)

diff --git a/src/jalview/gui/Help.java b/src/jalview/gui/Help.java
index f2d8113..9d8955f 100644
--- a/src/jalview/gui/Help.java
+++ b/src/jalview/gui/Help.java
@@ -20,6 +20,7 @@
  */
 package jalview.gui;
 
+import java.awt.Point;
 import java.net.URL;
 
 import javax.help.BadIDException;
@@ -54,9 +55,7 @@ public class Help
     }
   }
 
-  private static final long HALF_A_MO = 500; // half a second
-
-  private static long lastOpenedTime = 0L;
+  private static HelpBroker hb;
 
   /**
    * Not instantiable
@@ -67,42 +66,50 @@ public class Help
   }
 
   /**
-   * Show help text in a new window. But do nothing if within half a second of
-   * the last invocation.
-   * 
-   * This is a workaround for issue JAL-914 - both Desktop and AlignFrame
-   * responding to F1 key, resulting in duplicate help windows opened.
+   * Shows the help window, at the entry specified by the given helpId
    * 
    * @param id
-   *          TODO
    * 
    * @throws HelpSetException
    */
   public static void showHelpWindow(HelpId id) throws HelpSetException
   {
-    long timeNow = System.currentTimeMillis();
+    ClassLoader cl = Desktop.class.getClassLoader();
+    URL url = HelpSet.findHelpSet(cl, "help/help"); // $NON-NLS-$
+    HelpSet hs = new HelpSet(cl, url);
 
-    if (timeNow - lastOpenedTime > HALF_A_MO)
+    if (hb == null)
     {
-      lastOpenedTime = timeNow;
-      ClassLoader cl = Desktop.class.getClassLoader();
-      URL url = HelpSet.findHelpSet(cl, "help/help"); // $NON-NLS-$
-      HelpSet hs = new HelpSet(cl, url);
+      /*
+       * create help broker first time (only)
+       */
+      hb = hs.createHelpBroker();
+    }
 
-      HelpBroker hb = hs.createHelpBroker();
-      try
-      {
-        hb.setCurrentID(id.toString());
-      } catch (BadIDException bad)
-      {
-        System.out.println("Bad help link: " + id.toString()
-                + ": must match a target in help.jhm");
-        throw bad;
-      }
-      hb.setDisplayed(true);
+    try
+    {
+      hb.setCurrentID(id.toString());
+    } catch (BadIDException bad)
+    {
+      System.out.println("Bad help link: " + id.toString()
+              + ": must match a target in help.jhm");
+      throw bad;
     }
+
+    /*
+     * set Help visible - at its current location if it is already shown,
+     * else at a location as determined by the window manager
+     */
+    Point p = hb.getLocation();
+    hb.setLocation(p);
+    hb.setDisplayed(true);
   }
 
+  /**
+   * Show the Help window at the root entry
+   * 
+   * @throws HelpSetException
+   */
   public static void showHelpWindow() throws HelpSetException
   {
     showHelpWindow(HelpId.Home);
-- 
1.7.10.2