JavaScript port: desktop scrollbars for mouse-driven browsers

CodenameOne/src/com/codename1/ui/Component.java

@@ -6382,7 +6382,15 @@ private boolean handleInteractiveScrollPress(int x, int y) {
             int trackTop = absY + scrollTrackY;
             int trackLeft = absX + scrollTrackX;
             if (x >= trackLeft && x < trackLeft + scrollTrackW && y >= trackTop && y < trackTop + scrollTrackH) {
-                pageScroll(true, y < thumbTop);
+                if (getUIManager().getLookAndFeel().isInteractiveScrollTrackJump()) {
+                    // jump the thumb's center to the click and keep it grabbed, so the
+                    // same press can go on to drag it
+                    draggingScrollThumbY = true;
+                    scrollThumbGrabOffset = scrollThumbH / 2;
+                    dragScrollThumb(x, y);
+                } else {
+                    pageScroll(true, y < thumbTop);
+                }
                 return true;
             }
         }
@@ -6399,7 +6407,13 @@ private boolean handleInteractiveScrollPress(int x, int y) {
             int trackLeft = absX + hScrollTrackX;
             int trackTop = absY + hScrollTrackY;
             if (x >= trackLeft && x < trackLeft + hScrollTrackW && y >= trackTop && y < trackTop + hScrollTrackH) {
-                pageScroll(false, x < thumbLeft);
+                if (getUIManager().getLookAndFeel().isInteractiveScrollTrackJump()) {
+                    draggingScrollThumbX = true;
+                    scrollThumbGrabOffset = hScrollThumbW / 2;
+                    dragScrollThumb(x, y);
+                } else {
+                    pageScroll(false, x < thumbLeft);
+                }
                 return true;
             }
         }

CodenameOne/src/com/codename1/ui/plaf/LookAndFeel.java

@@ -109,6 +109,10 @@ public abstract class LookAndFeel {
     /// when the content is much taller/wider than the viewport. Resolved from the
     /// {@code scrollThumbMinSizeInt} theme constant, defaulting to roughly 4mm.
     private int interactiveScrollThumbMin;
+    /// When true a click on an interactive scrollbar's track moves the thumb to the click and
+    /// keeps it grabbed, instead of paging by one viewport. Resolved from the
+    /// {@code interactiveScrollTrackJumpBool} theme constant, off by default.
+    private boolean interactiveScrollTrackJump;
     private int fadeScrollBarSpeed = 5;
     private int fadeScrollEdgeLength = 15;
     private Image fadeScrollTop;
@@ -1099,6 +1103,7 @@ public void refreshTheme(boolean completeClear) {
         interactiveScroll = manager.isThemeConstant("interactiveScrollBool", false);
         interactiveScrollThumbMin = manager.getThemeConstant("scrollThumbMinSizeInt",
                 Display.getInstance().convertToPixels(4f));
+        interactiveScrollTrackJump = manager.isThemeConstant("interactiveScrollTrackJumpBool", false);
         initScroll();
         if (menuRenderer != null) {
             if (menuRenderer instanceof Component) {
@@ -1644,6 +1649,17 @@ public boolean isInteractiveScroll() {
         return interactiveScroll;
     }
 
+    /// Indicates whether a click on an interactive scrollbar's track jumps the thumb to the
+    /// click position (and keeps it grabbed for dragging) rather than paging one viewport
+    /// toward it. Controlled by the {@code interactiveScrollTrackJumpBool} theme constant.
+    ///
+    /// #### Returns
+    ///
+    /// true if a track click jumps to the clicked position
+    public boolean isInteractiveScrollTrackJump() {
+        return interactiveScrollTrackJump;
+    }
+
     /// Scrollbar thumb used for interactive desktop scrollbars. It renders its selected style
     /// when the pointer hovers the thumb and its pressed style while the thumb is being dragged,
     /// giving the desktop-conventional highlight feedback. The visual state is pushed in by the

Ports/JavaScriptPort/src/main/java/com/codename1/impl/html5/HTML5Implementation.java

@@ -5378,6 +5378,18 @@ public void installNativeTheme(){
             // undefined StatusBar UIID would also paint an opaque strip there).
             tp.put("@paintsTitleBarBool", "false");
 
+            // A browser driven by a mouse gets desktop scrollbars: a thumb that can be grabbed
+            // and dragged, and a track that pages on click. Without this constant the core
+            // treats a press on the scrollbar as a press on the content, so dragging the thumb
+            // became a touch swipe and scrolled the opposite way. The JavaSE port injects the
+            // same constant for desktop builds. ANY fine pointer qualifies, not only the
+            // primary one: a touch laptop still has its mouse, and the scrollbar only claims
+            // presses that land on it, so a finger swipe over the content still scrolls. A
+            // theme that sets the constant itself keeps its own value.
+            if (!tp.containsKey("@interactiveScrollBool") && matchesMediaQuery("(any-pointer: fine)")) {
+                tp.put("@interactiveScrollBool", "true");
+            }
+
             // Before the theme applies: a desktop theme sets commandBehavior Native, and
             // setCommandBehavior normalises that to the default for good when the port reports no
             // native menu bar at that moment -- which it does until the HTML chrome exists. Forms

maven/core-unittests/src/test/java/com/codename1/ui/InteractiveScrollbarTest.java

@@ -1,3 +1,25 @@
+/*
+ * Copyright (c) 2026, Codename One and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Codename One designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Codename One through http://www.codenameone.com/ if you
+ * need additional information or have any questions.
+ */
 package com.codename1.ui;
 
 import com.codename1.junit.FormTest;
@@ -125,6 +147,40 @@ void trackClickBelowThumbPagesDown() {
         sc.pointerReleased(px, py);
     }
 
+    @FormTest
+    void trackClickJumpsToPositionWhenEnabled() {
+        setInteractiveScroll(true);
+        Hashtable props = new Hashtable();
+        props.put("@interactiveScrollTrackJumpBool", "true");
+        UIManager.getInstance().addThemeProps(props);
+        assertTrue(UIManager.getInstance().getLookAndFeel().isInteractiveScrollTrackJump());
+        try {
+            Container sc = scrollableContainer(8000);
+            int thumbH = sc.getHeight() / 5;
+            injectVerticalThumb(sc, 0, thumbH);
+
+            // click the middle of the track: the thumb centers there, i.e. half the range
+            int px = sc.getAbsoluteX() + sc.getWidth() - GUTTER / 2;
+            int py = sc.getAbsoluteY() + sc.getHeight() / 2;
+            sc.pointerPressed(px, py);
+            assertTrue(sc.isInteractiveScrollThumbGrabbed(), "a jump keeps the thumb grabbed for dragging");
+            int max = sc.getScrollDimension().getHeight() - sc.getHeight();
+            int expected = max / 2;
+            assertTrue(Math.abs(sc.getScrollY() - expected) <= max / 50,
+                    "a track click should jump to the clicked position, got " + sc.getScrollY()
+                    + " expected about " + expected);
+
+            int mid = sc.getScrollY();
+            sc.pointerDragged(px, py + 50);
+            assertTrue(sc.getScrollY() > mid, "the same press goes on to drag the thumb");
+            sc.pointerReleased(px, py + 50);
+            assertFalse(sc.isInteractiveScrollThumbGrabbed());
+        } finally {
+            props.put("@interactiveScrollTrackJumpBool", "false");
+            UIManager.getInstance().addThemeProps(props);
+        }
+    }
+
     @FormTest
     void disabledIsInert() {
         setInteractiveScroll(false);