Improves UI on Linux

Author: emmanue1

app/src/main/groovy/org/jd/gui/controller/MainController.groovy

@@ -28,6 +28,7 @@ import org.jd.gui.service.indexer.IndexerService
 import org.jd.gui.service.mainpanel.PanelFactoryService
 import org.jd.gui.service.pastehandler.PasteHandlerService
 import org.jd.gui.service.actions.ContextualActionsFactoryService
+import org.jd.gui.service.platform.PlatformService
 import org.jd.gui.service.preferencespanel.PreferencesPanelService
 import org.jd.gui.service.sourcesaver.SourceSaverService
 import org.jd.gui.service.treenode.TreeNodeFactoryService
@@ -42,6 +43,7 @@ import org.jd.gui.spi.TreeNodeFactory
 import org.jd.gui.spi.TypeFactory
 import org.jd.gui.spi.UriLoader
 import org.jd.gui.util.net.UriUtil
+import org.jd.gui.util.swing.SwingUtil
 
 import javax.swing.Action
 import javax.swing.Icon
@@ -90,6 +92,12 @@ class MainController implements API {
 	MainController(SwingBuilder swing, Configuration configuration) {
         this.swing = swing
         this.configuration = configuration
+
+        if (PlatformService.instance.isLinux) {
+            // Fix for GTKLookAndFeel
+            SwingUtil.installGtkPopupBugWorkaround()
+        }
+
         // Create main frame
         mainView = new MainView(
             swing,

app/src/main/groovy/org/jd/gui/util/swing/SwingUtil.groovy

@@ -0,0 +1,136 @@
+/*
+ * Copyright (c) 2008-2015 Emmanuel Dupuy
+ * This program is made available under the terms of the GPLv3 License.
+ */
+
+package org.jd.gui.util.swing
+
+import groovy.transform.CompileStatic
+
+import javax.swing.JComponent
+import javax.swing.JPopupMenu
+import javax.swing.JSeparator
+import javax.swing.LookAndFeel
+import javax.swing.UIManager
+import java.lang.reflect.Field
+import java.lang.reflect.Method
+
+/**
+ * See: https://www.ailis.de/~k/archives/67-Workaround-for-borderless-Java-Swing-menus-on-Linux.html
+ */
+@CompileStatic
+class SwingUtil {
+    /*
+     * This is free and unencumbered software released into the public domain.
+     *
+     * Anyone is free to copy, modify, publish, use, compile, sell, or
+     * distribute this software, either in source code form or as a compiled
+     * binary, for any purpose, commercial or non-commercial, and by any
+     * means.
+     *
+     * In jurisdictions that recognize copyright laws, the author or authors
+     * of this software dedicate any and all copyright interest in the
+     * software to the public domain. We make this dedication for the benefit
+     * of the public at large and to the detriment of our heirs and
+     * successors. We intend this dedication to be an overt act of
+     * relinquishment in perpetuity of all present and future rights to this
+     * software under copyright law.
+     *
+     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+     * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+     * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+     * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+     * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+     * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+     * OTHER DEALINGS IN THE SOFTWARE.
+     *
+     * For more information, please refer to <http://unlicense.org/>
+     */
+
+    /**
+     * Swing menus are looking pretty bad on Linux when the GTK LaF is used (See
+     * bug #6925412). It will most likely never be fixed anytime soon so this
+     * method provides a workaround for it. It uses reflection to change the GTK
+     * style objects of Swing so popup menu borders have a minimum thickness of
+     * 1 and menu separators have a minimum vertical thickness of 1.
+     */
+    public static void installGtkPopupBugWorkaround() {
+        // Get current look-and-feel implementation class
+        LookAndFeel laf = UIManager.getLookAndFeel();
+        Class<?> lafClass = laf.getClass();
+
+        // Do nothing when not using the problematic LaF
+        if (!lafClass.getName().equals("com.sun.java.swing.plaf.gtk.GTKLookAndFeel")) return;
+
+        // We do reflection from here on. Failure is silently ignored. The
+        // workaround is simply not installed when something goes wrong here
+        try {
+            // Access the GTK style factory
+            Field field = lafClass.getDeclaredField("styleFactory");
+            boolean accessible = field.isAccessible();
+            field.setAccessible(true);
+            Object styleFactory = field.get(laf);
+            field.setAccessible(accessible);
+
+            // Fix the horizontal and vertical thickness of popup menu style
+            Object style = getGtkStyle(styleFactory, new JPopupMenu(), "POPUP_MENU");
+            fixGtkThickness(style, "yThickness");
+            fixGtkThickness(style, "xThickness");
+
+            // Fix the vertical thickness of the popup menu separator style
+            style = getGtkStyle(styleFactory, new JSeparator(), "POPUP_MENU_SEPARATOR");
+            fixGtkThickness(style, "yThickness");
+        } catch (Exception e) {
+            // Silently ignored. Workaround can't be applied.
+        }
+    }
+
+    /**
+     * Called internally by installGtkPopupBugWorkaround to fix the thickness
+     * of a GTK style field by setting it to a minimum value of 1.
+     *
+     * @param style
+     *            The GTK style object.
+     * @param fieldName
+     *            The field name.
+     * @throws Exception
+     *             When reflection fails.
+     */
+    private static void fixGtkThickness(Object style, String fieldName) throws Exception {
+        Field field = style.getClass().getDeclaredField(fieldName);
+        boolean accessible = field.isAccessible();
+        field.setAccessible(true);
+        field.setInt(style, Math.max(1, field.getInt(style)));
+        field.setAccessible(accessible);
+    }
+
+    /**
+     * Called internally by installGtkPopupBugWorkaround. Returns a specific
+     * GTK style object.
+     *
+     * @param styleFactory
+     *            The GTK style factory.
+     * @param component
+     *            The target component of the style.
+     * @param regionName
+     *            The name of the target region of the style.
+     * @return The GTK style.
+     * @throws Exception
+     *             When reflection fails.
+     */
+    private static Object getGtkStyle(Object styleFactory, JComponent component, String regionName) throws Exception {
+        // Create the region object
+        Class<?> regionClass = Class.forName("javax.swing.plaf.synth.Region");
+        Field field = regionClass.getField(regionName);
+        Object region = field.get(regionClass);
+
+        // Get and return the style
+        Class<?> styleFactoryClass = styleFactory.getClass();
+        Method method = styleFactoryClass.getMethod("getStyle", JComponent.class, regionClass);
+        boolean accessible = method.isAccessible();
+        method.setAccessible(true);
+        Object style = method.invoke(styleFactory, component, region);
+        method.setAccessible(accessible);
+        return style;
+    }
+}

app/src/main/groovy/org/jd/gui/view/PreferencesView.groovy

@@ -89,6 +89,8 @@ class PreferencesView implements PreferencesPanel.PreferencesPanelChangeListener
                     preferredHeight = maxHeight
                 preferencesScrollPane.preferredSize = new Dimension(400, preferredHeight)
 
+                minimumSize = new Dimension(300, 200)
+
                 pack()
                 locationRelativeTo = parent
             }