build, versioning and cross-platform about dlg

src/main/java/com/sparrowwallet/sparrow/AboutController.java

@@ -1,11 +1,20 @@
 package com.sparrowwallet.sparrow;
 
 import javafx.event.ActionEvent;
+import javafx.fxml.FXML;
+import javafx.scene.control.Label;
 import javafx.stage.Stage;
 
 public class AboutController {
     private Stage stage;
 
+    @FXML
+    private Label title;
+
+    public void initializeView() {
+        title.setText(MainApp.APP_NAME + " " + MainApp.APP_VERSION);
+    }
+
     public void setStage(Stage stage) {
         this.stage = stage;
     }

src/main/java/com/sparrowwallet/sparrow/AppController.java

@@ -87,6 +87,9 @@ public class AppController implements Initializable {
     @FXML
     private Menu fileMenu;
 
+    @FXML
+    private Menu helpMenu;
+
     @FXML
     private MenuItem openTransactionIdItem;
 
@@ -344,9 +347,15 @@ public class AppController implements Initializable {
             tk.setApplicationMenu(defaultApplicationMenu);
 
             fileMenu.getItems().removeIf(item -> item.getStyleClass().contains("macHide"));
+            helpMenu.getItems().removeIf(item -> item.getStyleClass().contains("macHide"));
         }
     }
 
+    public void showAbout(ActionEvent event) {
+        Stage aboutStage = getAboutStage();
+        aboutStage.show();
+    }
+
     private Stage getAboutStage() {
         try {
             FXMLLoader loader = new FXMLLoader(AppController.class.getResource("about.fxml"));
@@ -354,11 +363,12 @@ public class AppController implements Initializable {
             AboutController controller = loader.getController();
 
             Stage stage = new Stage();
-            stage.setTitle("About Sparrow");
+            stage.setTitle("About " + MainApp.APP_NAME);
             stage.initStyle(StageStyle.UNDECORATED);
             stage.setResizable(false);
             stage.setScene(new Scene(root));
             controller.setStage(stage);
+            controller.initializeView();
 
             return stage;
         } catch(IOException e) {

src/main/java/com/sparrowwallet/sparrow/MainApp.java

@@ -22,6 +22,7 @@ import java.util.Optional;
 
 public class MainApp extends Application {
     public static final String APP_NAME = "Sparrow";
+    public static final String APP_VERSION = "0.9.1";
 
     private Stage mainStage;