Fix showing a gray horizontal line in component list cell

HMCL/src/main/java/org/jackhuang/hmcl/ui/construct/ComponentList.java

@@ -106,18 +106,14 @@ public class ComponentList extends Control {
         protected Skin(ComponentList control) {
             super(control);
 
-            list = MappedObservableList.create(control.getContent(), this::mapper);
+            list = MappedObservableList.create(control.getContent(), ComponentListCell::new);
+            ListFirstElementListener.observe(list,
+                    first -> first.getStyleClass().setAll("options-list-item-ahead"),
+                    last -> last.getStyleClass().setAll("options-list-item"));
 
             VBox vbox = new VBox();
             Bindings.bindContent(vbox.getChildren(), list);
             getChildren().setAll(vbox);
         }
-
-        private Node mapper(Node node) {
-            StackPane child = new StackPane();
-            child.getChildren().add(new ComponentListCell(node));
-            child.getStyleClass().add("options-list-item");
-            return child;
-        }
     }
 }

HMCL/src/main/java/org/jackhuang/hmcl/ui/construct/ComponentListCell.java

@@ -122,10 +122,7 @@ class ComponentListCell extends StackPane {
             VBox container = new VBox();
             container.setStyle("-fx-padding: 8 0 0 0;");
             FXUtils.setLimitHeight(container, 0);
-            Rectangle clipRect = new Rectangle();
+            FXUtils.setOverflowHidden(container, true);
-            clipRect.widthProperty().bind(container.widthProperty());
-            clipRect.heightProperty().bind(container.heightProperty());
-            container.setClip(clipRect);
             container.getChildren().setAll(content);
 
             VBox holder = new VBox();

HMCL/src/main/java/org/jackhuang/hmcl/ui/construct/ListFirstElementListener.java

@@ -0,0 +1,59 @@
+package org.jackhuang.hmcl.ui.construct;
+
+import javafx.collections.ListChangeListener;
+import javafx.collections.ObservableList;
+
+import java.util.function.Consumer;
+
+public class ListFirstElementListener<T> implements ListChangeListener<T> {
+
+    private final Consumer<? super T> first, last;
+
+    public ListFirstElementListener(Consumer<? super T> first, Consumer<? super T> last) {
+        this.first = first;
+        this.last = last;
+    }
+
+    @Override
+    public void onChanged(Change<? extends T> c) {
+        ObservableList<? extends T> list = c.getList();
+        if (list.isEmpty()) return;
+        while (c.next()) {
+            int from = c.getFrom();
+            int to = c.getTo();
+
+            if (c.wasPermutated()) {
+                for (int i = from; i < to; ++i) {
+                    int newIdx = c.getPermutation(i);
+                    if (i == 0 && newIdx != 0)
+                        last.accept(list.get(newIdx));
+                    else if (i != 0 && newIdx == 0)
+                        first.accept(list.get(newIdx));
+                }
+            } else {
+                if (c.wasRemoved()) {
+                    if (!list.isEmpty() && from == 0)
+                        first.accept(list.get(0));
+                }
+                if (c.wasAdded()) {
+                    for (int i = from; i < to; ++i) {
+                        if (i == 0)
+                            first.accept(list.get(0));
+                        else
+                            last.accept(list.get(i));
+                    }
+                    if (list.size() > to)
+                        last.accept(list.get(to));
+                }
+            }
+        }
+    }
+
+    public static <T> void observe(ObservableList<? extends T> list, Consumer<? super T> first, Consumer<? super T> last) {
+        for (int i = 0; i < list.size(); ++i) {
+            if (i == 0) first.accept(list.get(i));
+            else last.accept(list.get(i));
+        }
+        list.addListener(new ListFirstElementListener<>(first, last));
+    }
+}