Add property to configure the 'not_enabled' css styling for widgets

core/ui/src/main/java/org/phoebus/ui/Preferences.java

@@ -7,6 +7,10 @@
  *******************************************************************************/
 package org.phoebus.ui;
 
+import java.net.URI;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
 import org.phoebus.framework.preferences.AnnotatedPreferences;
 import org.phoebus.framework.preferences.Preference;
 
@@ -17,6 +21,8 @@
 
 public class Preferences
 {
+	public final static Logger logger = Logger.getLogger(Preferences.class.getPackageName());
+
 	/** splash */
 	public static final String SPLASH = "splash";
     /** default_apps */
@@ -99,6 +105,8 @@ public class Preferences
     @Preference public static String window_title_format;
     /** default_window_title **/
     @Preference public static String default_window_title;
+    /** Custom stylings file */
+    @Preference public static String custom_css_styling;
 
     static
     {
@@ -108,5 +116,19 @@ public class Preferences
         // (PVASettings cannot use Preferences.max_array_formatting
         //  since the PVA library may be used standalone)
         System.setProperty("EPICS_PVA_MAX_ARRAY_FORMATTING", Integer.toString(max_array_formatting));
+
+        // Check once if the custom style sheet is accessible
+        if (!custom_css_styling.isBlank())
+        {
+             try
+             {
+                 new URI(custom_css_styling).toURL().openStream().close();
+             }
+             catch (Exception ex)
+             {
+                 logger.log(Level.WARNING, custom_css_styling + " is inaccessible", ex);
+                 custom_css_styling = "";
+             }
+        }
     }
 }

core/ui/src/main/java/org/phoebus/ui/javafx/Styles.java

@@ -7,6 +7,8 @@
  ******************************************************************************/
 package org.phoebus.ui.javafx;
 
+import org.phoebus.ui.Preferences;
+
 import javafx.scene.Node;
 import javafx.scene.Scene;
 
@@ -24,6 +26,10 @@ public static void setSceneStyle(final Scene scene)
     {
         final String css = Styles.class.getResource("csstudio.css").toExternalForm();
         set(scene, css);
+        if (!Preferences.custom_css_styling.isEmpty())
+        {
+            set(scene, Preferences.custom_css_styling);
+        }
     }
 
     /** Apply style sheet to scene (but only once)

core/ui/src/main/resources/phoebus_ui_preferences.properties

@@ -188,3 +188,9 @@ documentation_location=
 # When there is no active tab, the default_window_title is used instead.
 window_title_format=CS-Studio: %s
 default_window_title=CS-Studio
+
+# Custom stylings .css file allows users to override Phoebus and JavaFX
+# default stylings.Set the full path to the .css file
+# For a system file use syntax; 'file:</path/to/custom.css>'
+# For a file served over http use syntax: 'http://<address:port/custom.css>'
+custom_css_styling=