add "tool tips" to content viewers

CoreComponentInterfaces/src/org/sleuthkit/autopsy/corecomponentinterfaces/DataContentViewer.java

@@ -37,6 +37,12 @@ public interface DataContentViewer {
      * Returns the title of this viewer. 
      */
     public String getTitle();
+    
+    /**
+     * Returns a short description of this viewer to use as a tool tip for
+     * its tab. 
+     */
+    public String getToolTip();
 
     /**
      * Get new DataContentViewer instance. (This method is weird. We use the

CoreComponents/src/org/sleuthkit/autopsy/corecomponents/DataContentTopComponent.java

@@ -194,7 +194,8 @@ public final class DataContentTopComponent extends TopComponent implements DataC
             for (DataContentViewer factory : Lookup.getDefault().lookupAll(DataContentViewer.class)) {
                 DataContentViewer dcv = factory.getInstance();
                 this.viewers.add(new UpdateWrapper(dcv));
-                dataContentTabbedPane.addTab(dcv.getTitle(), dcv.getComponent());
+                dataContentTabbedPane.addTab(dcv.getTitle(), null,
+                        dcv.getComponent(), dcv.getToolTip());
             }
         }
 

CoreComponents/src/org/sleuthkit/autopsy/corecomponents/DataContentViewerHex.java

@@ -284,6 +284,12 @@ public class DataContentViewerHex extends javax.swing.JPanel implements DataCont
     public String getTitle() {
         return "Hex View";
     }
+    
+    @Override
+    public String getToolTip() {
+        return "Displays the binary contents of a file as hexidecimal, with "
+                + "bytes that are displayable as ASCII characters on the right.";
+    }
 
     @Override
     public DataContentViewer getInstance() {

CoreComponents/src/org/sleuthkit/autopsy/corecomponents/DataContentViewerPicture.java

@@ -116,6 +116,11 @@ public class DataContentViewerPicture extends javax.swing.JPanel implements Data
     public String getTitle() {
         return "Picture View";
     }
+    
+    @Override
+    public String getToolTip() {
+        return "Displays supported image files.";
+    }
 
     @Override
     public DataContentViewer getInstance() {

CoreComponents/src/org/sleuthkit/autopsy/corecomponents/DataContentViewerString.java

@@ -278,6 +278,11 @@ public class DataContentViewerString extends javax.swing.JPanel implements DataC
     public String getTitle() {
         return "String View";
     }
+    
+    @Override
+    public String getToolTip() {
+        return "Displays ASCII strings extracted from the file.";
+    }
 
     @Override
     public DataContentViewer getInstance() {