Refactored checking for which GTK version is loaded. The logic has been

simplified.

src/dorkbox/util/Desktop.java

@@ -25,6 +25,7 @@ import java.net.URI;
 import java.net.URISyntaxException;
 
 import dorkbox.util.jna.linux.Gtk2;
+import dorkbox.util.jna.linux.GtkCheck;
 import dorkbox.util.jna.linux.GtkEventDispatch;
 import dorkbox.util.process.ShellExecutor;
 
@@ -73,7 +74,7 @@ class Desktop {
         // Prefer JNA method over AWT, since there are fewer chances for JNA to fail (even though they call the same method)
         // Additionally, xdg-open  can cause problems in Linux with Chrome installed but not the default browser. It will crash Chrome
         //      if Chrome was open before this app opened a URL
-        if ((OS.isUnix() || OS.isLinux()) && OSUtil.DesktopEnv.isGtkLoaded) {
+        if ((OS.isUnix() || OS.isLinux()) && GtkCheck.isGtkLoaded) {
             GtkEventDispatch.dispatch(new Runnable() {
                 @Override
                 public
@@ -132,7 +133,7 @@ class Desktop {
         }
 
         // Prevent GTK2/3 conflict caused by Desktop.getDesktop(), which is GTK2 only (via AWT)
-        if ((OS.isUnix() || OS.isLinux()) && OSUtil.DesktopEnv.isGtkLoaded) {
+        if ((OS.isUnix() || OS.isLinux()) && GtkCheck.isGtkLoaded) {
             GtkEventDispatch.dispatch(new Runnable() {
                 @Override
                 public
@@ -181,7 +182,7 @@ class Desktop {
         }
         // Prevent GTK2/3 conflict caused by Desktop.getDesktop(), which is GTK2 only (via AWT)
         // Prefer JNA method over AWT, since there are fewer chances for JNA to fail (even though they call the same method)
-        else if ((OS.isUnix() || OS.isLinux()) && OSUtil.DesktopEnv.isGtkLoaded) {
+        else if ((OS.isUnix() || OS.isLinux()) && GtkCheck.isGtkLoaded) {
             // it can actually be MORE that just "file://" (ie, "ftp://" is legit as well)
             if (!path.contains("://")) {
                 path = "file://" + path;

src/dorkbox/util/OSUtil.java

@@ -402,21 +402,6 @@ class OSUtil {
 
     public static
     class DesktopEnv {
-        /**
-         * Determine if the application is running via GTK2. This does not cause GTK to load, where calls to Gtk.isGtk2 will
-         */
-        public static volatile boolean isGtk2 = false;
-
-        /**
-         * Determine if the application is running via GTK3. This does not cause GTK to load, where calls to Gtk.isGtk3 will
-         */
-        public static volatile boolean isGtk3 = false;
-
-        /**
-         * Determine if the application has loaded GTK yet or not. This does not cause GTK to load, where calls to Gtk.isLoaded will
-         */
-        public static volatile boolean isGtkLoaded = false;
-
         public enum Env {
             Gnome,
             KDE,

src/dorkbox/util/SwingUtil.java

@@ -168,6 +168,9 @@ class SwingUtil {
     /**
      * Checks to see if GTK is loaded by Swing, and if so - which version is loaded.
      *
+     * NOTE: if the UI uses the 'getSystemLookAndFeelClassName' and is on Linux and it's the GtkLookAndFeel, this will cause GTK2
+     * to get loaded first, which will cause conflicts if one tries to use GTK3
+     *
      * @return the version of GTK loaded (if any) otherwise 0 for no version of GTK is loaded
      */
     public static

src/dorkbox/util/jna/linux/GtkCheck.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2017 dorkbox, llc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package dorkbox.util.jna.linux;
+
+import dorkbox.util.JavaFX;
+import dorkbox.util.SwingUtil;
+import dorkbox.util.Swt;
+
+/**
+ * Accessor methods/logic for determining if GTK is already loaded by the Swing/JavaFX/SWT, or if GTK has been manually loaded via
+ * GtkEventDispatch.startGui().
+ */
+@SuppressWarnings("WeakerAccess")
+public
+class GtkCheck {
+    /**
+     * Only valid if `isGtkLoaded=true`. Determine if the application is running via GTK2.
+     * <p>
+     * This does not cause GTK to load, where calls to Gtk.isGtk2 will
+     */
+    public static volatile boolean isGtk2 = false;
+
+    /**
+     * Only valid if `isGtkLoaded=true`. Determine if the application is running via GTK3.
+     * <p>
+     * This does not cause GTK to load, where calls to Gtk.isGtk2 will
+     */
+    public static volatile boolean isGtk3 = false;
+
+    /**
+     * Determine if the application has *MANUALLY* loaded GTK yet or not. This does not cause GTK to load, where calls to Gtk.isLoaded will
+     */
+    public static volatile boolean isGtkLoaded = false;
+
+    /**
+     * This method is agnostic w.r.t. how GTK is loaded, which can be manually loaded or loaded via JavaFX/SWT/Swing.
+     *
+     * @return the version of GTK loaded. 0=no GTK loaded, 2=GTK2, 3=GTK3
+     */
+    public static
+    int getLoadedGtkVersion() {
+        // if we have ALREADY loaded GTK, then return that information.
+        if (isGtkLoaded) {
+            if (isGtk3) {
+                return 3;
+            } else {
+                return 2;
+            }
+        }
+
+        if (Swt.isLoaded) {
+            if (Swt.isGtk3) {
+                return 3;
+            } else {
+                return 2;
+            }
+        }
+
+        if (JavaFX.isLoaded) {
+            if (JavaFX.isGtk3) {
+                return 3;
+            } else {
+                return 2;
+            }
+        }
+
+        // now check if swing has loaded GTK from the Look and Feel
+        return SwingUtil.getLoadedGtkVersion();
+    }
+}

src/dorkbox/util/jna/linux/GtkLoader.java

@@ -21,7 +21,6 @@ import com.sun.jna.Function;
 import com.sun.jna.NativeLibrary;
 
 import dorkbox.util.OS;
-import dorkbox.util.OSUtil;
 import dorkbox.util.Swt;
 import dorkbox.util.jna.JnaHelper;
 
@@ -211,9 +210,9 @@ class GtkLoader {
         }
 
         // This is so that queries for the GTK version DO NOT try to load GTK
-        OSUtil.DesktopEnv.isGtk2 = isGtk2;
-        OSUtil.DesktopEnv.isGtk3 = isGtk3;
-        OSUtil.DesktopEnv.isGtkLoaded = isLoaded;
+        GtkCheck.isGtk2 = isGtk2;
+        GtkCheck.isGtk3 = isGtk3;
+        GtkCheck.isGtkLoaded = isLoaded;
 
         if (shouldLoadGtk) {
             if (!_isLoaded) {