From 203bf38b210cc2782812ca61ba91f71ac7d149f2 Mon Sep 17 00:00:00 2001
From: David Richardson <david.richardson@enquora.com>
Date: Thu, 22 Oct 2026 12:36:32 -0600
Subject: [PATCH] AppKit: Size vertical scrollers by scroller style in
 CPScrollView
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CPScrollView's frame and content size calculations sized the vertical scroller with scrollerWidthForControlSize:, passing a scroller style, so it always took the legacy width.

* CPScrollView: Use scrollerWidthInStyle: for the vertical scroller in +contentSizeForFrameSize:… and +frameSizeForContentSize:….
* CPScrollViewTest: Add tests for both methods with a scroller whose widths differ by style.
---
 AppKit/CPScrollView.j           |  4 +--
 Tests/AppKit/CPScrollViewTest.j | 43 +++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/AppKit/CPScrollView.j b/AppKit/CPScrollView.j
index 45f98d5f0..716d34550 100644
--- a/AppKit/CPScrollView.j
+++ b/AppKit/CPScrollView.j
@@ -207,7 +207,7 @@ var CPScrollerStyleGlobal                       = CPScrollerStyleOverlay,
         bounds.size.height -= [horizontalScrollerClass scrollerWidthInStyle:scrollerStyle];
 
     if (verticalScrollerClass)
-        bounds.size.width -= [verticalScrollerClass scrollerWidthForControlSize:scrollerStyle];
+        bounds.size.width -= [verticalScrollerClass scrollerWidthInStyle:scrollerStyle];
 
     return bounds.size;
 }
@@ -240,7 +240,7 @@ var CPScrollerStyleGlobal                       = CPScrollerStyleOverlay,
         frameSize.height += [horizontalScrollerClass scrollerWidthInStyle:scrollerStyle];
 
     if (verticalScrollerClass)
-        frameSize.width += [verticalScrollerClass scrollerWidthForControlSize:scrollerStyle];
+        frameSize.width += [verticalScrollerClass scrollerWidthInStyle:scrollerStyle];
 
     return frameSize;
 }
diff --git a/Tests/AppKit/CPScrollViewTest.j b/Tests/AppKit/CPScrollViewTest.j
index be937a1c9..15ee3ec5c 100644
--- a/Tests/AppKit/CPScrollViewTest.j
+++ b/Tests/AppKit/CPScrollViewTest.j
@@ -379,5 +379,48 @@
     [self assertSize:expected.size equals:actual.size message:message]
 }
 
+- (void)testFrameSizeForContentSizeUsesScrollerStyleForBothScrollers
+{
+    var frameSize = [CPScrollView frameSizeForContentSize:CGSizeMake(100.0, 100.0)
+                                  horizontalScrollerClass:[_CPScrollViewTestScroller class]
+                                    verticalScrollerClass:[_CPScrollViewTestScroller class]
+                                               borderType:CPNoBorder
+                                              controlSize:CPRegularControlSize
+                                            scrollerStyle:CPScrollerStyleOverlay];
+
+    [self assertSize:CGSizeMake(105.0, 105.0) equals:frameSize message:@"both scroller widths come from scrollerWidthInStyle:"];
+}
+
+- (void)testContentSizeForFrameSizeUsesScrollerStyleForBothScrollers
+{
+    var contentSize = [CPScrollView contentSizeForFrameSize:CGSizeMake(100.0, 100.0)
+                                    horizontalScrollerClass:[_CPScrollViewTestScroller class]
+                                      verticalScrollerClass:[_CPScrollViewTestScroller class]
+                                                 borderType:CPNoBorder
+                                                controlSize:CPRegularControlSize
+                                              scrollerStyle:CPScrollerStyleOverlay];
+
+    [self assertSize:CGSizeMake(95.0, 95.0) equals:contentSize message:@"both scroller widths come from scrollerWidthInStyle:"];
+}
+
 @end
 
+
+/*!
+    A scroller whose widths differ by style, and whose control-size width differs
+    from both, so a size calculation that uses the wrong method is detectable
+    regardless of the theme.
+*/
+@implementation _CPScrollViewTestScroller : CPScroller
+
++ (float)scrollerWidthInStyle:(CPScrollerStyle)aStyle
+{
+    return aStyle === CPScrollerStyleOverlay ? 5.0 : 20.0;
+}
+
++ (float)scrollerWidthForControlSize:(CPControlSize)aControlSize
+{
+    return 99.0;
+}
+
+@end