tor-browser

commit 0a310bf4d7c6921c559a7ffb248c164c6095c7cc
parent c141abb081a2a3d2ef3b4aeb70b9476a6b84677e
Author: Greg Stoll <gstoll@mozilla.com>
Date:   Mon, 20 Oct 2025 18:18:35 +0000

Bug 1956974 - make thin scrollbars have thumb buttons on Windows r=spohl,win-reviewers,desktop-theme-reviewers,handyman,emilio

Per the bug, all thin scrollbars in the Windows OS (that I could find)
do have thumb buttons for scrolling up/down, so we should match that.

Differential Revision: https://phabricator.services.mozilla.com/D269217

Diffstat:
M
widget/ScrollbarDrawing.cpp
 | 
6
------
M
widget/ScrollbarDrawing.h
 | 
1
-
M
widget/ScrollbarDrawingWin.cpp
 | 
5
-----
M
widget/ScrollbarDrawingWin11.cpp
 | 
3
---
M
widget/Theme.cpp
 | 
27
++++++++++++---------------

5 files changed, 12 insertions(+), 30 deletions(-)
diff --git a/widget/ScrollbarDrawing.cpp b/widget/ScrollbarDrawing.cpp
@@ -72,12 +72,6 @@ bool ScrollbarDrawing::IsScrollbarWidthThin(const ComputedStyle& aStyle) {
   return scrollbarWidth == StyleScrollbarWidth::Thin;
 }
 
-/*static*/
-bool ScrollbarDrawing::IsScrollbarWidthThin(nsIFrame* aFrame) {
-  ComputedStyle* style = nsLayoutUtils::StyleForScrollbar(aFrame);
-  return IsScrollbarWidthThin(*style);
-}
-
 CSSIntCoord ScrollbarDrawing::GetCSSScrollbarSize(StyleScrollbarWidth aWidth,
                                                   Overlay aOverlay) const {
   return mScrollbarSize[aWidth == StyleScrollbarWidth::Thin]
diff --git a/widget/ScrollbarDrawing.h b/widget/ScrollbarDrawing.h
@@ -55,7 +55,6 @@ class ScrollbarDrawing {
   static bool IsParentScrollbarHoveredOrActive(nsIFrame* aFrame);
 
   static bool IsScrollbarWidthThin(const ComputedStyle& aStyle);
-  static bool IsScrollbarWidthThin(nsIFrame* aFrame);
 
   CSSIntCoord GetCSSScrollbarSize(StyleScrollbarWidth, Overlay) const;
   LayoutDeviceIntCoord GetScrollbarSize(const nsPresContext*,
diff --git a/widget/ScrollbarDrawingWin.cpp b/widget/ScrollbarDrawingWin.cpp
@@ -24,11 +24,6 @@ LayoutDeviceIntSize ScrollbarDrawingWin::GetMinimumWidgetSize(
     case StyleAppearance::ScrollbarbuttonDown:
     case StyleAppearance::ScrollbarbuttonLeft:
     case StyleAppearance::ScrollbarbuttonRight:
-      // For scrollbar-width:thin, we don't display the buttons.
-      if (IsScrollbarWidthThin(aFrame)) {
-        return LayoutDeviceIntSize{};
-      }
-      [[fallthrough]];
     case StyleAppearance::ScrollbarVertical:
     case StyleAppearance::ScrollbarHorizontal:
     case StyleAppearance::ScrollbarthumbVertical:
diff --git a/widget/ScrollbarDrawingWin11.cpp b/widget/ScrollbarDrawingWin11.cpp
@@ -59,9 +59,6 @@ LayoutDeviceIntSize ScrollbarDrawingWin11::GetMinimumWidgetSize(
     case StyleAppearance::ScrollbarbuttonDown:
     case StyleAppearance::ScrollbarbuttonLeft:
     case StyleAppearance::ScrollbarbuttonRight: {
-      if (IsScrollbarWidthThin(aFrame)) {
-        return {};
-      }
       const LayoutDeviceIntCoord size =
           ScrollbarDrawing::GetScrollbarSize(aPresContext, aFrame);
       return LayoutDeviceIntSize{
diff --git a/widget/Theme.cpp b/widget/Theme.cpp
@@ -1234,21 +1234,18 @@ bool Theme::DoDrawWidgetBackground(PaintBackendData& aPaintData,
     case StyleAppearance::ScrollbarbuttonDown:
     case StyleAppearance::ScrollbarbuttonLeft:
     case StyleAppearance::ScrollbarbuttonRight: {
-      // For scrollbar-width:thin, we don't display the buttons.
-      if (!ScrollbarDrawing::IsScrollbarWidthThin(aFrame)) {
-        if constexpr (std::is_same_v<PaintBackendData, WebRenderBackendData>) {
-          // TODO: Need to figure out how to best draw this using WR.
-          return false;
-        } else {
-          bool isHorizontal =
-              aAppearance == StyleAppearance::ScrollbarbuttonLeft ||
-              aAppearance == StyleAppearance::ScrollbarbuttonRight;
-          auto kind = ComputeScrollbarKind(aFrame, isHorizontal);
-          GetScrollbarDrawing().PaintScrollbarButton(
-              aPaintData, aAppearance, devPxRect, kind, aFrame,
-              *nsLayoutUtils::StyleForScrollbar(aFrame), elementState, colors,
-              dpiRatio);
-        }
+      if constexpr (std::is_same_v<PaintBackendData, WebRenderBackendData>) {
+        // TODO: Need to figure out how to best draw this using WR.
+        return false;
+      } else {
+        bool isHorizontal =
+            aAppearance == StyleAppearance::ScrollbarbuttonLeft ||
+            aAppearance == StyleAppearance::ScrollbarbuttonRight;
+        auto kind = ComputeScrollbarKind(aFrame, isHorizontal);
+        GetScrollbarDrawing().PaintScrollbarButton(
+            aPaintData, aAppearance, devPxRect, kind, aFrame,
+            *nsLayoutUtils::StyleForScrollbar(aFrame), elementState, colors,
+            dpiRatio);
       }
       break;
     }