suggest connecting to broadcast a finalized transaction if offlineand a server is configured

src/main/java/com/sparrowwallet/sparrow/control/ConfirmationAlert.java

@@ -0,0 +1,39 @@
+package com.sparrowwallet.sparrow.control;
+
+import com.sparrowwallet.sparrow.AppServices;
+import javafx.geometry.Insets;
+import javafx.scene.control.Alert;
+import javafx.scene.control.ButtonType;
+import javafx.scene.control.CheckBox;
+import javafx.scene.control.Label;
+import javafx.scene.layout.VBox;
+
+import static com.sparrowwallet.sparrow.AppServices.getActiveWindow;
+import static com.sparrowwallet.sparrow.AppServices.setStageIcon;
+
+public class ConfirmationAlert extends Alert {
+    private final CheckBox dontAskAgain;
+
+    public ConfirmationAlert(String title, String contentText, ButtonType... buttons) {
+        super(AlertType.CONFIRMATION, contentText, buttons);
+
+        initOwner(getActiveWindow());
+        setStageIcon(getDialogPane().getScene().getWindow());
+        getDialogPane().getScene().getStylesheets().add(AppServices.class.getResource("general.css").toExternalForm());
+        setTitle(title);
+        setHeaderText(title);
+
+        VBox contentBox = new VBox(20);
+        contentBox.setPadding(new Insets(10, 20, 10, 20));
+        Label contentLabel = new Label(contentText);
+        contentLabel.setWrapText(true);
+        dontAskAgain = new CheckBox("Don't ask again");
+        contentBox.getChildren().addAll(contentLabel, dontAskAgain);
+
+        getDialogPane().setContent(contentBox);
+    }
+
+    public boolean isDontAskAgain() {
+        return dontAskAgain.isSelected();
+    }
+}

src/main/java/com/sparrowwallet/sparrow/io/Config.java

@@ -52,6 +52,7 @@ public class Config {
     private boolean showDeprecatedImportExport = false;
     private boolean signBsmsExports = false;
     private boolean preventSleep = false;
+    private Boolean connectToBroadcast;
     private List<File> recentWalletFiles;
     private Integer keyDerivationPeriod;
     private long dustAttackThreshold = DUST_ATTACK_THRESHOLD_SATS;
@@ -348,6 +349,16 @@ public class Config {
 
     public void setPreventSleep(boolean preventSleep) {
         this.preventSleep = preventSleep;
+        flush();
+    }
+
+    public Boolean getConnectToBroadcast() {
+        return connectToBroadcast;
+    }
+
+    public void setConnectToBroadcast(Boolean connectToBroadcast) {
+        this.connectToBroadcast = connectToBroadcast;
+        flush();
     }
 
     public List<File> getRecentWalletFiles() {

src/main/java/com/sparrowwallet/sparrow/transaction/HeadersController.java

@@ -1559,6 +1559,23 @@ public class HeadersController extends TransactionFormController implements Init
 
             signButtonBox.setVisible(false);
             broadcastButtonBox.setVisible(true);
+
+            if(Config.get().hasServer() && !AppServices.isConnected() && !AppServices.isConnecting()) {
+                if(Config.get().getConnectToBroadcast() == null) {
+                    Platform.runLater(() -> {
+                        ConfirmationAlert confirmationAlert = new ConfirmationAlert("Connect to broadcast?", "Connect to the configured server to broadcast the transaction?", ButtonType.NO, ButtonType.YES);
+                        Optional<ButtonType> optType = confirmationAlert.showAndWait();
+                        if(confirmationAlert.isDontAskAgain() && optType.isPresent()) {
+                            Config.get().setConnectToBroadcast(optType.get() == ButtonType.YES);
+                        }
+                        if(optType.isPresent() && optType.get() == ButtonType.YES) {
+                            EventManager.get().post(new RequestConnectEvent());
+                        }
+                    });
+                } else if(Config.get().getConnectToBroadcast()) {
+                    Platform.runLater(() -> EventManager.get().post(new RequestConnectEvent()));
+                }
+            }
         }
     }