change styling of volume preferences

src/main/resources/css/light_theme.css

@@ -910,3 +910,13 @@
 	-fx-border-style: solid inside;
 	-fx-border-width: 1px;
 }
+/*******************************************************************************
+ *                                                                             *
+ * Separator                                                                   *
+ *                                                                             *
+ ******************************************************************************/
+
+.separator {
+  -fx-padding: 1px;
+  -fx-background-color: CONTROL_BORDER_DISABLED;
+}

src/main/resources/fxml/preferences_volume.fxml

@@ -6,6 +6,7 @@
 <?import javafx.scene.control.Button?>
 <?import javafx.scene.control.ChoiceBox?>
 <?import javafx.scene.control.Label?>
+<?import javafx.scene.control.Separator?>
 <?import javafx.scene.layout.HBox?>
 <?import javafx.scene.layout.VBox?>
 <VBox xmlns:fx="http://javafx.com/fxml"
@@ -21,17 +22,16 @@
 			<ChoiceBox fx:id="volumeTypeChoiceBox"/>
 		</HBox>
 
-		<HBox spacing="12" alignment="CENTER_LEFT" visible="${controller.loopbackPortSupported}">
+		<HBox spacing="12" alignment="CENTER_LEFT" visible="${controller.loopbackPortSupported}" managed="${controller.loopbackPortSupported}">
 			<Label text="%preferences.volume.tcp.port"/>
 			<NumericTextField fx:id="loopbackPortField"/>
 			<Button text="%generic.button.apply" fx:id="loopbackPortApplyButton" onAction="#doChangeLoopbackPort"/>
 		</HBox>
 
+		<Separator orientation="HORIZONTAL"/>
+
 		<Label text="%preferences.volume.supportedFeatures"/>
 		<VBox spacing="12">
-			<padding>
-				<Insets left="24"/>
-			</padding>
 			<Label text="%preferences.volume.feature.mountToDir" visible="${controller.mountToDirSupported}" managed="${controller.mountToDirSupported}" contentDisplay="LEFT">
 				<graphic>
 					<FontAwesome5IconView glyph="CHECK"/>