config: add `scrollbar` config to control when scrollbars appear

macos/Sources/Ghostty/Ghostty.Config.swift

@@ -603,6 +603,17 @@ extension Ghostty {
             let str = String(cString: ptr)
             return MacShortcuts(rawValue: str) ?? defaultValue
         }
+
+        var scrollbar: Scrollbar {
+            let defaultValue = Scrollbar.system
+            guard let config = self.config else { return defaultValue }
+            var v: UnsafePointer<Int8>? = nil
+            let key = "scrollbar"
+            guard ghostty_config_get(config, &v, key, UInt(key.count)) else { return defaultValue }
+            guard let ptr = v else { return defaultValue }
+            let str = String(cString: ptr)
+            return Scrollbar(rawValue: str) ?? defaultValue
+        }
     }
 }
 
@@ -641,6 +652,11 @@ extension Ghostty.Config {
         case ask
     }
 
+    enum Scrollbar: String {
+        case system
+        case never
+    }
+
     enum ResizeOverlay : String {
         case always
         case never

macos/Sources/Ghostty/SurfaceScrollView.swift

@@ -1,4 +1,5 @@
 import SwiftUI
+import Combine
 
 /// Wraps a Ghostty surface view in an NSScrollView to provide native macOS scrollbar support.
 ///
@@ -16,6 +17,7 @@ class SurfaceScrollView: NSView {
     private let documentView: NSView
     private let surfaceView: Ghostty.SurfaceView
     private var observers: [NSObjectProtocol] = []
+    private var cancellables: Set<AnyCancellable> = []
     private var isLiveScrolling = false
     
     /// The last row position sent via scroll_to_row action. Used to avoid
@@ -28,7 +30,7 @@ class SurfaceScrollView: NSView {
         // The scroll view is our outermost view that controls all our scrollbar
         // rendering and behavior.
         scrollView = NSScrollView()
-        scrollView.hasVerticalScroller = true
+        scrollView.hasVerticalScroller = false
         scrollView.hasHorizontalScroller = false
         scrollView.autohidesScrollers = true
         scrollView.usesPredominantAxisScrolling = true
@@ -49,6 +51,9 @@ class SurfaceScrollView: NSView {
         // Our scroll view is our only view
         addSubview(scrollView)
         
+        // Apply initial scrollbar settings
+        synchronizeAppearance()
+        
         // We listen for scroll events through bounds notifications on our NSClipView.
         // This is based on: https://christiantietze.de/posts/2018/07/synchronize-nsscrollview/
         scrollView.contentView.postsBoundsChangedNotifications = true
@@ -93,6 +98,15 @@ class SurfaceScrollView: NSView {
         ) { [weak self] _ in
             self?.handleLiveScroll()
         })
+        
+        // Listen for derived config changes to update scrollbar settings live
+        surfaceView.$derivedConfig
+            .sink { [weak self] _ in
+                DispatchQueue.main.async { [weak self] in
+                    self?.synchronizeAppearance()
+                }
+            }
+            .store(in: &cancellables)
     }
     
     required init?(coder: NSCoder) {

macos/Sources/Ghostty/SurfaceView_AppKit.swift

@@ -1532,6 +1532,7 @@ extension Ghostty {
             let macosWindowShadow: Bool
             let windowTitleFontFamily: String?
             let windowAppearance: NSAppearance?
+            let scrollbar: Ghostty.Config.Scrollbar
 
             init() {
                 self.backgroundColor = Color(NSColor.windowBackgroundColor)
@@ -1539,6 +1540,7 @@ extension Ghostty {
                 self.macosWindowShadow = true
                 self.windowTitleFontFamily = nil
                 self.windowAppearance = nil
+                self.scrollbar = .system
             }
 
             init(_ config: Ghostty.Config) {
@@ -1547,6 +1549,7 @@ extension Ghostty {
                 self.macosWindowShadow = config.macosWindowShadow
                 self.windowTitleFontFamily = config.windowTitleFontFamily
                 self.windowAppearance = .init(ghosttyConfig: config)
+                self.scrollbar = config.scrollbar
             }
         }
 

src/config/Config.zig

@@ -1197,6 +1197,24 @@ input: RepeatableReadableIO = .{},
 /// This can be changed at runtime but will only affect new terminal surfaces.
 @"scrollback-limit": usize = 10_000_000, // 10MB
 
+/// Control when the scrollbar is shown to scroll the scrollback buffer.
+///
+/// The default value is `system`.
+///
+/// Valid values:
+///
+///   * `system` - Respect the system settings for when to show scrollbars.
+///     For example, on macOS, this will respect the "Scrollbar behavior"
+///     system setting which by default usually only shows scrollbars while
+///     actively scrolling or hovering the gutter.
+///
+///   * `never` - Never show a scrollbar. You can still scroll using the mouse,
+///     keybind actions, etc. but you will not have a visual UI widget showing
+///     a scrollbar.
+///
+/// This only applies to macOS currently. GTK doesn't yet support scrollbars.
+scrollbar: Scrollbar = .system,
+
 /// Match a regular expression against the terminal text and associate clicking
 /// it with an action. This can be used to match URLs, file paths, etc. Actions
 /// can be opening using the system opener (e.g. `open` or `xdg-open`) or
@@ -8379,6 +8397,12 @@ pub const WindowPadding = struct {
     }
 };
 
+/// See scrollbar
+pub const Scrollbar = enum {
+    system,
+    never,
+};
+
 /// See scroll-to-bottom
 pub const ScrollToBottom = packed struct {
     keystroke: bool = true,