ADD: DatasetSelectorDialog() "OK" button changes:

- renamed to "Open in Imagej"
- is disabled if there's any tree item selected,
  or non-selectable items are clicked
- ENTER key associated with the button

src/main/java/org/janelia/saalfeldlab/n5/ui/DatasetSelectorDialog.java

@@ -30,6 +30,7 @@
 import java.awt.GridBagConstraints;
 import java.awt.GridBagLayout;
 import java.awt.Insets;
+import java.awt.event.KeyEvent;
 import java.io.File;
 import java.net.URI;
 import java.nio.file.Paths;
@@ -49,6 +50,7 @@
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 
+import javax.swing.KeyStroke;
 import javax.swing.JButton;
 import javax.swing.JCheckBox;
 import javax.swing.JFileChooser;
@@ -95,6 +97,8 @@
 import net.imglib2.util.Pair;
 import se.sawano.java.text.AlphanumericComparator;
 
+import static javax.swing.JComponent.WHEN_IN_FOCUSED_WINDOW;
+
 public class DatasetSelectorDialog {
 
 	/**
@@ -342,6 +346,10 @@ public void run(final Consumer<DataSelection> okCallback) {
 
 		// ok and cancel buttons
 		okBtn.addActionListener(e -> ok());
+		okBtn.registerKeyboardAction(a -> ok(),
+				  "n5_open_button",
+				  KeyStroke.getKeyStroke(KeyEvent.VK_ENTER,0,true),
+				  WHEN_IN_FOCUSED_WINDOW);
 		cancelBtn.addActionListener(e -> cancel());
 		dialog.setVisible(true);
 	}
@@ -486,7 +494,7 @@ private JFrame buildDialog() {
 		cbot.anchor = GridBagConstraints.CENTER;
 		panel.add(messageLabel, cbot);
 
-		okBtn = new JButton("OK");
+		okBtn = new JButton("Open in Imagej");
 		cbot.gridx = 4;
 		cbot.ipadx = 20;
 		cbot.anchor = GridBagConstraints.EAST;
@@ -503,6 +511,15 @@ private JFrame buildDialog() {
 		panel.add(cancelBtn, cbot);
 
 		containerTree.addMouseListener(new NodePopupMenu(this).getPopupListener());
+		containerTree.addTreeSelectionListener(tsl -> {
+			if (containerTree.getSelectionCount() == 0) {
+				okBtn.setEnabled( false );
+			} else {
+				int selectedRow = containerTree.getSelectionRows()[0];
+				N5SwingTreeNode n = (N5SwingTreeNode)containerTree.getPathForRow(selectedRow).getLastPathComponent();
+				okBtn.setEnabled( selectionFilter.test(n.getMetadata()) );
+			}
+		});
 
 		dialog.pack();
 		return dialog;