Migrate UI forms from GUI designer to programmatic layout

src/main/java/de/espend/idea/php/annotation/ui/SettingsForm.java

@@ -1,31 +1,50 @@
 package de.espend.idea.php.annotation.ui;
 
 import com.intellij.openapi.options.Configurable;
+import com.intellij.ui.IdeBorderFactory;
+import com.intellij.ui.TitledSeparator;
+import com.intellij.util.ui.FormBuilder;
+import com.intellij.util.ui.JBUI;
 import de.espend.idea.php.annotation.ApplicationSettings;
 import de.espend.idea.php.annotation.util.PluginUtil;
 import org.jetbrains.annotations.Nls;
 import org.jetbrains.annotations.Nullable;
 
 import javax.swing.*;
-import java.awt.event.MouseAdapter;
-import java.awt.event.MouseEvent;
+import java.awt.*;
 
 /**
  * @author Daniel Espendiller <daniel@espendiller.net>
  */
 public class SettingsForm implements Configurable {
-    private JCheckBox appendRoundBracket;
-    private JPanel panel;
-    private JButton buttonCleanIndex;
+    private final JCheckBox appendRoundBracket = new JCheckBox("Insert round bracket after class name");
+    private final JButton buttonCleanIndex = new JButton("Schedule annotation reindex");
+    private final JPanel panel;
 
     public SettingsForm() {
-        buttonCleanIndex.addMouseListener(new MouseAdapter() {
-            @Override
-            public void mouseClicked(MouseEvent e) {
-                PluginUtil.forceReindex();
-                super.mouseClicked(e);
-            }
-        });
+        this.panel = createPanel();
+
+        buttonCleanIndex.addActionListener(e -> PluginUtil.forceReindex());
+        updateUIFromSettings();
+    }
+
+    private JPanel createPanel() {
+        JPanel actionsPanel = new JPanel(new FlowLayout(FlowLayout.LEFT, 0, 0));
+        actionsPanel.add(buttonCleanIndex);
+
+        JPanel content = FormBuilder.createFormBuilder()
+            .addComponent(new TitledSeparator("Actions"))
+            .addComponent(actionsPanel, JBUI.scale(6))
+            .addVerticalGap(JBUI.scale(12))
+            .addComponent(new TitledSeparator("Autocomplete (Annotations)"))
+            .addComponent(appendRoundBracket, JBUI.scale(6))
+            .getPanel();
+
+        JPanel root = new JPanel(new BorderLayout());
+        root.setBorder(IdeBorderFactory.createEmptyBorder(JBUI.insets(10, 0, 0, 0)));
+        root.add(content, BorderLayout.NORTH);
+
+        return root;
     }
 
     @Nls
@@ -48,9 +67,7 @@ public JComponent createComponent() {
 
     @Override
     public boolean isModified() {
-        return
-            !appendRoundBracket.isSelected() == ApplicationSettings.getInstance().appendRoundBracket
-            ;
+        return appendRoundBracket.isSelected() != ApplicationSettings.getInstance().appendRoundBracket;
     }
 
     @Override