Merge branch 'feature/JAL-3063jaxbNoCastor' into feature/JAL-3141_Create_a_backup_whe...
[jalview.git] / src / jalview / gui / Desktop.java
index bf729f6..aefcf08 100644 (file)
@@ -26,17 +26,20 @@ import jalview.api.AlignViewportI;
 import jalview.api.AlignmentViewPanel;
 import jalview.bin.Cache;
 import jalview.bin.Jalview;
+import jalview.io.BackupFiles;
 import jalview.io.DataSourceType;
 import jalview.io.FileFormat;
 import jalview.io.FileFormatException;
 import jalview.io.FileFormatI;
 import jalview.io.FileFormats;
 import jalview.io.FileLoader;
+import jalview.io.FormatAdapter;
 import jalview.io.IdentifyFile;
 import jalview.io.JalviewFileChooser;
 import jalview.io.JalviewFileView;
 import jalview.jbgui.GSplitFrame;
 import jalview.jbgui.GStructureViewer;
+import jalview.project.Jalview2XML;
 import jalview.structure.StructureSelectionManager;
 import jalview.urls.IdOrgSettings;
 import jalview.util.ImageMaker;
@@ -68,8 +71,7 @@ import java.awt.dnd.DropTargetEvent;
 import java.awt.dnd.DropTargetListener;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
-import java.awt.event.FocusEvent;
-import java.awt.event.FocusListener;
+import java.awt.event.InputEvent;
 import java.awt.event.KeyEvent;
 import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;
@@ -93,10 +95,13 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.Semaphore;
 
 import javax.swing.AbstractAction;
+import javax.swing.Action;
+import javax.swing.ActionMap;
 import javax.swing.Box;
 import javax.swing.BoxLayout;
 import javax.swing.DefaultDesktopManager;
 import javax.swing.DesktopManager;
+import javax.swing.InputMap;
 import javax.swing.JButton;
 import javax.swing.JCheckBox;
 import javax.swing.JComboBox;
@@ -118,6 +123,8 @@ import javax.swing.event.InternalFrameEvent;
 import javax.swing.event.MenuEvent;
 import javax.swing.event.MenuListener;
 
+import org.stackoverflowusers.file.WindowsShortcut;
+
 /**
  * Jalview Desktop
  * 
@@ -346,10 +353,6 @@ public class Desktop extends jalview.jbgui.GDesktop
     boolean showjconsole = jalview.bin.Cache.getDefault("SHOW_JAVA_CONSOLE",
             false);
     desktop = new MyDesktopPane(selmemusage);
-    if (Platform.isAMac())
-    {
-      desktop.setDoubleBuffered(false);
-    }
     showMemusage.setSelected(selmemusage);
     desktop.setBackground(Color.white);
     getContentPane().setLayout(new BorderLayout());
@@ -363,7 +366,12 @@ public class Desktop extends jalview.jbgui.GDesktop
     // This line prevents Windows Look&Feel resizing all new windows to maximum
     // if previous window was maximised
     desktop.setDesktopManager(
-            new MyDesktopManager(new DefaultDesktopManager()));
+            new MyDesktopManager(
+                    (Platform.isWindows() ? new DefaultDesktopManager()
+                            : Platform.isAMac()
+                                    ? new AquaInternalFrameManager(
+                                            desktop.getDesktopManager())
+                                    : desktop.getDesktopManager())));
 
     Rectangle dims = getLastKnownDimensions("");
     if (dims != null)
@@ -433,24 +441,6 @@ public class Desktop extends jalview.jbgui.GDesktop
     });
     desktop.addMouseListener(ma);
 
-    this.addFocusListener(new FocusListener()
-    {
-
-      @Override
-      public void focusLost(FocusEvent e)
-      {
-        // TODO Auto-generated method stub
-
-      }
-
-      @Override
-      public void focusGained(FocusEvent e)
-      {
-        Cache.log.debug("Relaying windows after focus gain");
-        // make sure that we sort windows properly after we gain focus
-        instance.relayerWindows();
-      }
-    });
     this.setDropTarget(new java.awt.dnd.DropTarget(desktop, this));
     // Spawn a thread that shows the splashscreen
     SwingUtilities.invokeLater(new Runnable()
@@ -531,7 +521,7 @@ public class Desktop extends jalview.jbgui.GDesktop
   {
     final Desktop me = this;
     // Thread off the news reader, in case there are connection problems.
-    addDialogThread(new Runnable()
+    new Thread(new Runnable()
     {
       @Override
       public void run()
@@ -542,13 +532,13 @@ public class Desktop extends jalview.jbgui.GDesktop
         showNews.setVisible(true);
         Cache.log.debug("Completed news thread.");
       }
-    });
+    }).start();
   }
 
   public void getIdentifiersOrgData()
   {
     // Thread off the identifiers fetcher
-    addDialogThread(new Runnable()
+    new Thread(new Runnable()
     {
       @Override
       public void run()
@@ -565,7 +555,8 @@ public class Desktop extends jalview.jbgui.GDesktop
                   + e.getMessage());
         }
       }
-    });
+    }).start();
+    ;
   }
 
   @Override
@@ -868,13 +859,8 @@ public class Desktop extends jalview.jbgui.GDesktop
     frame.setResizable(resizable);
     frame.setMaximizable(resizable);
     frame.setIconifiable(resizable);
-    if (Platform.isAMac())
-    {
-      frame.setIconifiable(false);
-      frame.setFrameIcon(null);
-      // frame.setDesktopIcon(null);
-      frame.setDoubleBuffered(false);
-    }
+    frame.setOpaque(false);
+
     if (frame.getX() < 1 && frame.getY() < 1)
     {
       frame.setLocation(xOffset * openFrameCount,
@@ -894,6 +880,10 @@ public class Desktop extends jalview.jbgui.GDesktop
         JInternalFrame itf = desktop.getSelectedFrame();
         if (itf != null)
         {
+          if (itf instanceof AlignFrame)
+          {
+            Jalview.setCurrentAlignFrame((AlignFrame) itf);
+          }
           itf.requestFocus();
         }
       }
@@ -920,16 +910,6 @@ public class Desktop extends jalview.jbgui.GDesktop
           menuItem.removeActionListener(menuItem.getActionListeners()[0]);
         }
         windowMenu.remove(menuItem);
-        JInternalFrame itf = desktop.getSelectedFrame();
-        if (itf != null)
-        {
-          itf.requestFocus();
-          if (itf instanceof AlignFrame)
-          {
-            Jalview.setCurrentAlignFrame((AlignFrame) itf);
-          }
-        }
-        System.gc();
       };
     });
 
@@ -949,6 +929,8 @@ public class Desktop extends jalview.jbgui.GDesktop
       }
     });
 
+    setKeyBindings(frame);
+
     desktop.add(frame);
 
     windowMenu.add(menuItem);
@@ -968,6 +950,42 @@ public class Desktop extends jalview.jbgui.GDesktop
     }
   }
 
+  /**
+   * Add key bindings to a JInternalFrame so that Ctrl-W and Cmd-W will close
+   * the window
+   * 
+   * @param frame
+   */
+  private static void setKeyBindings(JInternalFrame frame)
+  {
+    @SuppressWarnings("serial")
+    final Action closeAction = new AbstractAction()
+    {
+      @Override
+      public void actionPerformed(ActionEvent e)
+      {
+        frame.dispose();
+      }
+    };
+
+    /*
+     * set up key bindings for Ctrl-W and Cmd-W, with the same (Close) action
+     */
+    KeyStroke ctrlWKey = KeyStroke.getKeyStroke(KeyEvent.VK_W,
+            InputEvent.CTRL_DOWN_MASK);
+    KeyStroke cmdWKey = KeyStroke.getKeyStroke(KeyEvent.VK_W,
+            Toolkit.getDefaultToolkit().getMenuShortcutKeyMask());
+
+    InputMap inputMap = frame
+            .getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
+    String ctrlW = ctrlWKey.toString();
+    inputMap.put(ctrlWKey, ctrlW);
+    inputMap.put(cmdWKey, ctrlW);
+
+    ActionMap actionMap = frame.getActionMap();
+    actionMap.put(ctrlW, closeAction);
+  }
+
   @Override
   public void lostOwnership(Clipboard clipboard, Transferable contents)
   {
@@ -1013,8 +1031,8 @@ public class Desktop extends jalview.jbgui.GDesktop
     // Java's Transferable for native dnd
     evt.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
     Transferable t = evt.getTransferable();
-    List<String> files = new ArrayList<String>();
-    List<DataSourceType> protocols = new ArrayList<DataSourceType>();
+    List<String> files = new ArrayList<>();
+    List<DataSourceType> protocols = new ArrayList<>();
 
     try
     {
@@ -1417,7 +1435,6 @@ public class Desktop extends jalview.jbgui.GDesktop
     {
       ssm.resetAll();
     }
-    System.gc();
   }
 
   @Override
@@ -1584,28 +1601,45 @@ public class Desktop extends jalview.jbgui.GDesktop
   }
 
   /**
-   * DOCUMENT ME!
-   * 
-   * @param e
-   *          DOCUMENT ME!
+   * Shows a file chooser dialog and writes out the current session as a Jalview
+   * project file
    */
   @Override
-  public void saveState_actionPerformed(ActionEvent e)
+  public void saveState_actionPerformed()
   {
-    JalviewFileChooser chooser = new JalviewFileChooser("jvp",
-            "Jalview Project");
+    saveState_actionPerformed(false);
+  }
 
-    chooser.setFileView(new JalviewFileView());
-    chooser.setDialogTitle(MessageManager.getString("label.save_state"));
+  public void saveState_actionPerformed(boolean saveAs)
+  {
+    java.io.File projectFile = getProjectFile();
+    // autoSave indicates we already have a file and don't need to ask
+    boolean autoSave = projectFile != null && !saveAs && BackupFiles.getEnabled();
 
-    int value = chooser.showSaveDialog(this);
+    System.out.println("autoSave="+autoSave+", projectFile='"+projectFile+"', saveAs="+saveAs+", Backups "+(BackupFiles.getEnabled()?"enabled":"disabled"));
 
-    if (value == JalviewFileChooser.APPROVE_OPTION)
+    boolean approveSave = false;
+    if (!autoSave)
     {
-      final Desktop me = this;
-      final java.io.File choice = chooser.getSelectedFile();
-      setProjectFile(choice);
+      JalviewFileChooser chooser = new JalviewFileChooser("jvp",
+              "Jalview Project");
 
+      chooser.setFileView(new JalviewFileView());
+      chooser.setDialogTitle(MessageManager.getString("label.save_state"));
+
+      int value = chooser.showSaveDialog(this);
+
+      if (value == JalviewFileChooser.APPROVE_OPTION)
+      {
+        projectFile = chooser.getSelectedFile();
+        setProjectFile(projectFile);
+        approveSave = true;
+      }
+    }
+
+    if (approveSave || autoSave) {
+      final Desktop me = this;
+      final java.io.File chosenFile = projectFile;
       new Thread(new Runnable()
       {
         @Override
@@ -1614,38 +1648,49 @@ public class Desktop extends jalview.jbgui.GDesktop
           // TODO: refactor to Jalview desktop session controller action.
           setProgressBar(MessageManager.formatMessage(
                   "label.saving_jalview_project", new Object[]
-                  { choice.getName() }), choice.hashCode());
+                  { chosenFile.getName() }), chosenFile.hashCode());
           jalview.bin.Cache.setProperty("LAST_DIRECTORY",
-                  choice.getParent());
+                  chosenFile.getParent());
           // TODO catch and handle errors for savestate
           // TODO prevent user from messing with the Desktop whilst we're saving
           try
           {
-            new Jalview2XML().saveState(choice);
+            BackupFiles backupfiles = new BackupFiles(chosenFile);
+
+            new Jalview2XML().saveState(backupfiles.getTempFile());
+
+            backupfiles.setWriteSuccess(true);
+            backupfiles.rollBackupsAndRenameTempFile();
           } catch (OutOfMemoryError oom)
           {
             new OOMWarning(
-                    "Whilst saving current state to " + choice.getName(),
+                    "Whilst saving current state to " + chosenFile.getName(),
                     oom);
           } catch (Exception ex)
           {
             Cache.log.error(
-                    "Problems whilst trying to save to " + choice.getName(),
+                    "Problems whilst trying to save to " + chosenFile.getName(),
                     ex);
             JvOptionPane.showMessageDialog(me,
                     MessageManager.formatMessage(
                             "label.error_whilst_saving_current_state_to",
                             new Object[]
-                            { choice.getName() }),
+                            { chosenFile.getName() }),
                     MessageManager.getString("label.couldnt_save_project"),
                     JvOptionPane.WARNING_MESSAGE);
           }
-          setProgressBar(null, choice.hashCode());
+          setProgressBar(null, chosenFile.hashCode());
         }
       }).start();
     }
   }
 
+  @Override
+  public void saveAsState_actionPerformed(ActionEvent e)
+  {
+    saveState_actionPerformed(true);
+  }
+
   private void setProjectFile(File choice)
   {
     this.projectFile = choice;
@@ -1657,19 +1702,18 @@ public class Desktop extends jalview.jbgui.GDesktop
   }
 
   /**
-   * DOCUMENT ME!
-   * 
-   * @param e
-   *          DOCUMENT ME!
+   * Shows a file chooser dialog and tries to read in the selected file as a
+   * Jalview project
    */
   @Override
-  public void loadState_actionPerformed(ActionEvent e)
+  public void loadState_actionPerformed()
   {
+    final String[] suffix = new String[] { "jvp", "jar" };
+    final String[] desc = new String[] { "Jalview Project",
+        "Jalview Project (old)" };
     JalviewFileChooser chooser = new JalviewFileChooser(
-            Cache.getProperty("LAST_DIRECTORY"), new String[]
-            { "jvp", "jar" },
-            new String[]
-            { "Jalview Project", "Jalview Project (old)" },
+            Cache.getProperty("LAST_DIRECTORY"), suffix,
+            desc,
             "Jalview Project");
     chooser.setFileView(new JalviewFileView());
     chooser.setDialogTitle(MessageManager.getString("label.restore_state"));
@@ -1722,7 +1766,7 @@ public class Desktop extends jalview.jbgui.GDesktop
 
   JPanel progressPanel;
 
-  ArrayList<JPanel> fileLoadingPanels = new ArrayList<JPanel>();
+  ArrayList<JPanel> fileLoadingPanels = new ArrayList<>();
 
   public void startLoading(final String fileName)
   {
@@ -1814,7 +1858,7 @@ public class Desktop extends jalview.jbgui.GDesktop
       // TODO: verify that frames are recoverable when in headless mode
       return null;
     }
-    List<AlignmentPanel> aps = new ArrayList<AlignmentPanel>();
+    List<AlignmentPanel> aps = new ArrayList<>();
     AlignFrame[] frames = getAlignFrames();
     if (frames == null)
     {
@@ -1849,7 +1893,7 @@ public class Desktop extends jalview.jbgui.GDesktop
    */
   public static AlignmentViewport[] getViewports(String sequenceSetId)
   {
-    List<AlignmentViewport> viewp = new ArrayList<AlignmentViewport>();
+    List<AlignmentViewport> viewp = new ArrayList<>();
     if (desktop != null)
     {
       AlignFrame[] frames = Desktop.getAlignFrames();
@@ -2362,12 +2406,12 @@ public class Desktop extends jalview.jbgui.GDesktop
           // SEQUENCE_ID which is not the default EMBL_EBI link
           ListIterator<String> li = links.listIterator();
           boolean check = false;
-          List<JLabel> urls = new ArrayList<JLabel>();
+          List<JLabel> urls = new ArrayList<>();
           while (li.hasNext())
           {
             String link = li.next();
             if (link.contains(SEQUENCE_ID)
-                    && !link.equals(UrlConstants.DEFAULT_STRING))
+                    && !UrlConstants.isDefaultString(link))
             {
               check = true;
               int barPos = link.indexOf("|");
@@ -2456,6 +2500,7 @@ public class Desktop extends jalview.jbgui.GDesktop
         Thread worker = new Thread(this);
         worker.start();
       }
+      repaint();
     }
 
     public boolean isShowMemoryUsage()
@@ -2519,14 +2564,6 @@ public class Desktop extends jalview.jbgui.GDesktop
     }
   }
 
-  /**
-   * fixes stacking order after a modal dialog to ensure windows that should be
-   * on top actually are
-   */
-  public void relayerWindows()
-  {
-
-  }
 
   /**
    * Accessor method to quickly get all the AlignmentFrames loaded.
@@ -2547,7 +2584,7 @@ public class Desktop extends jalview.jbgui.GDesktop
     {
       return null;
     }
-    List<AlignFrame> avp = new ArrayList<AlignFrame>();
+    List<AlignFrame> avp = new ArrayList<>();
     // REVERSE ORDER
     for (int i = frames.length - 1; i > -1; i--)
     {
@@ -2592,7 +2629,7 @@ public class Desktop extends jalview.jbgui.GDesktop
     {
       return null;
     }
-    List<GStructureViewer> avp = new ArrayList<GStructureViewer>();
+    List<GStructureViewer> avp = new ArrayList<>();
     // REVERSE ORDER
     for (int i = frames.length - 1; i > -1; i--)
     {
@@ -2735,8 +2772,8 @@ public class Desktop extends jalview.jbgui.GDesktop
   {
     if (progressBars == null)
     {
-      progressBars = new Hashtable<Long, JPanel>();
-      progressBarHandlers = new Hashtable<Long, IProgressIndicatorHandler>();
+      progressBars = new Hashtable<>();
+      progressBarHandlers = new Hashtable<>();
     }
 
     if (progressBars.get(new Long(id)) != null)
@@ -3329,13 +3366,67 @@ public class Desktop extends jalview.jbgui.GDesktop
     return groovyConsole;
   }
 
+  /**
+   * handles the payload of a drag and drop event.
+   * 
+   * TODO refactor to desktop utilities class
+   * 
+   * @param files
+   *          - Data source strings extracted from the drop event
+   * @param protocols
+   *          - protocol for each data source extracted from the drop event
+   * @param evt
+   *          - the drop event
+   * @param t
+   *          - the payload from the drop event
+   * @throws Exception
+   */
   public static void transferFromDropTarget(List<String> files,
           List<DataSourceType> protocols, DropTargetDropEvent evt,
           Transferable t) throws Exception
   {
 
     DataFlavor uriListFlavor = new DataFlavor(
-            "text/uri-list;class=java.lang.String");
+            "text/uri-list;class=java.lang.String"), urlFlavour = null;
+    try
+    {
+      urlFlavour = new DataFlavor(
+              "application/x-java-url; class=java.net.URL");
+    } catch (ClassNotFoundException cfe)
+    {
+      Cache.log.debug("Couldn't instantiate the URL dataflavor.", cfe);
+    }
+
+    if (urlFlavour != null && t.isDataFlavorSupported(urlFlavour))
+    {
+
+      try
+      {
+      java.net.URL url = (URL) t.getTransferData(urlFlavour);
+        // nb: java 8 osx bug https://bugs.openjdk.java.net/browse/JDK-8156099
+        // means url may be null.
+      if (url != null)
+      {
+        protocols.add(DataSourceType.URL);
+        files.add(url.toString());
+        Cache.log.debug("Drop handled as URL dataflavor "
+                + files.get(files.size() - 1));
+          return;
+        }
+        else
+        {
+          if (Platform.isAMac())
+          {
+            System.err.println(
+                    "Please ignore plist error - occurs due to problem with java 8 on OSX");
+          }
+          ;
+      }
+      } catch (Throwable ex)
+      {
+        Cache.log.debug("URL drop handler failed.", ex);
+      }
+    }
     if (t.isDataFlavorSupported(DataFlavor.javaFileListFlavor))
     {
       // Works on Windows and MacOSX
@@ -3363,63 +3454,112 @@ public class Desktop extends jalview.jbgui.GDesktop
         // fallback to text: workaround - on OSX where there's a JVM bug
         Cache.log.debug("standard URIListFlavor failed. Trying text");
         // try text fallback
-        data = (String) t.getTransferData(
-                new DataFlavor("text/plain;class=java.lang.String"));
-        if (Cache.log.isDebugEnabled())
+        DataFlavor textDf = new DataFlavor(
+                "text/plain;class=java.lang.String");
+        if (t.isDataFlavorSupported(textDf))
         {
-          Cache.log.debug("fallback returned " + data);
+          data = (String) t.getTransferData(textDf);
         }
+
+        Cache.log.debug("Plain text drop content returned "
+                + (data == null ? "Null - failed" : data));
+
       }
-      while (protocols.size() < files.size())
-      {
-        Cache.log.debug("Adding missing FILE protocol for "
-                + files.get(protocols.size()));
-        protocols.add(DataSourceType.FILE);
-      }
-      for (java.util.StringTokenizer st = new java.util.StringTokenizer(
-              data, "\r\n"); st.hasMoreTokens();)
+      if (data != null)
       {
-        added = true;
-        String s = st.nextToken();
-        if (s.startsWith("#"))
+        while (protocols.size() < files.size())
         {
-          // the line is a comment (as per the RFC 2483)
-          continue;
+          Cache.log.debug("Adding missing FILE protocol for "
+                  + files.get(protocols.size()));
+          protocols.add(DataSourceType.FILE);
         }
-        java.net.URI uri = new java.net.URI(s);
-        if (uri.getScheme().toLowerCase().startsWith("http"))
+        for (java.util.StringTokenizer st = new java.util.StringTokenizer(
+                data, "\r\n"); st.hasMoreTokens();)
         {
-          protocols.add(DataSourceType.URL);
-          files.add(uri.toString());
-        }
-        else
-        {
-          // otherwise preserve old behaviour: catch all for file objects
-          java.io.File file = new java.io.File(uri);
-          protocols.add(DataSourceType.FILE);
-          files.add(file.toString());
+          added = true;
+          String s = st.nextToken();
+          if (s.startsWith("#"))
+          {
+            // the line is a comment (as per the RFC 2483)
+            continue;
+          }
+          java.net.URI uri = new java.net.URI(s);
+          if (uri.getScheme().toLowerCase().startsWith("http"))
+          {
+            protocols.add(DataSourceType.URL);
+            files.add(uri.toString());
+          }
+          else
+          {
+            // otherwise preserve old behaviour: catch all for file objects
+            java.io.File file = new java.io.File(uri);
+            protocols.add(DataSourceType.FILE);
+            files.add(file.toString());
+          }
         }
       }
+
       if (Cache.log.isDebugEnabled())
       {
         if (data == null || !added)
         {
-          Cache.log.debug(
-                  "Couldn't resolve drop data. Here are the supported flavors:");
-          for (DataFlavor fl : t.getTransferDataFlavors())
+
+          if (t.getTransferDataFlavors() != null
+                  && t.getTransferDataFlavors().length > 0)
           {
             Cache.log.debug(
-                    "Supported transfer dataflavor: " + fl.toString());
-            Object df = t.getTransferData(fl);
-            if (df != null)
+                    "Couldn't resolve drop data. Here are the supported flavors:");
+            for (DataFlavor fl : t.getTransferDataFlavors())
             {
-              Cache.log.debug("Retrieves: " + df);
-            }
-            else
-            {
-              Cache.log.debug("Retrieved nothing");
+              Cache.log.debug(
+                      "Supported transfer dataflavor: " + fl.toString());
+              Object df = t.getTransferData(fl);
+              if (df != null)
+              {
+                Cache.log.debug("Retrieves: " + df);
+              }
+              else
+              {
+                Cache.log.debug("Retrieved nothing");
+              }
             }
           }
+          else
+          {
+            Cache.log.debug("Couldn't resolve dataflavor for drop: "
+                    + t.toString());
+          }
+        }
+      }
+    }
+    if (Platform.isWindows())
+
+    {
+      Cache.log.debug("Scanning dropped content for Windows Link Files");
+
+      // resolve any .lnk files in the file drop
+      for (int f = 0; f < files.size(); f++)
+      {
+        String source = files.get(f).toLowerCase();
+        if (protocols.get(f).equals(DataSourceType.FILE)
+                && (source.endsWith(".lnk") || source.endsWith(".url")
+                        || source.endsWith(".site")))
+        {
+          try {
+            File lf = new File(files.get(f));
+            // process link file to get a URL
+            Cache.log.debug("Found potential link file: " + lf);
+            WindowsShortcut wscfile = new WindowsShortcut(lf);
+            String fullname = wscfile.getRealFilename();
+            protocols.set(f, FormatAdapter.checkProtocol(fullname));
+            files.set(f, fullname);
+            Cache.log.debug("Parsed real filename " + fullname
+                    + " to extract protocol: " + protocols.get(f));
+          }
+          catch (Exception ex)
+          {
+            Cache.log.error("Couldn't parse "+files.get(f)+" as a link file.",ex);
+          }
         }
       }
     }
@@ -3434,4 +3574,41 @@ public class Desktop extends jalview.jbgui.GDesktop
   {
     Cache.setProperty(EXPERIMENTAL_FEATURES, Boolean.toString(selected));
   }
+
+  /**
+   * Answers a (possibly empty) list of any structure viewer frames (currently
+   * for either Jmol or Chimera) which are currently open. This may optionally
+   * be restricted to viewers of a specified class, or viewers linked to a
+   * specified alignment panel.
+   * 
+   * @param apanel
+   *          if not null, only return viewers linked to this panel
+   * @param structureViewerClass
+   *          if not null, only return viewers of this class
+   * @return
+   */
+  public List<StructureViewerBase> getStructureViewers(
+          AlignmentPanel apanel,
+          Class<? extends StructureViewerBase> structureViewerClass)
+  {
+    List<StructureViewerBase> result = new ArrayList<>();
+    JInternalFrame[] frames = Desktop.instance.getAllFrames();
+
+    for (JInternalFrame frame : frames)
+    {
+      if (frame instanceof StructureViewerBase)
+      {
+        if (structureViewerClass == null
+                || structureViewerClass.isInstance(frame))
+        {
+          if (apanel == null
+                  || ((StructureViewerBase) frame).isLinkedWith(apanel))
+          {
+            result.add((StructureViewerBase) frame);
+          }
+        }
+      }
+    }
+    return result;
+  }
 }