From 5bd7b4aaecc10caacec50dc481ec5ac19b1f0cce Mon Sep 17 00:00:00 2001
From: Daniel Imms <2193314+Tyriar@users.noreply.github.com>
Date: Thu, 28 Aug 2025 10:28:19 -0700
Subject: [PATCH 01/12] Bring back partial wheel tracking

Part of microsoft/vscode#224750
---
 src/browser/CoreBrowserTerminal.ts | 41 ++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/src/browser/CoreBrowserTerminal.ts b/src/browser/CoreBrowserTerminal.ts
index 14ff9433..37b33f7e 100644
--- a/src/browser/CoreBrowserTerminal.ts
+++ b/src/browser/CoreBrowserTerminal.ts
@@ -646,6 +646,10 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           if (deltaY === 0) {
             return false;
           }
+          const lines = self._consumeWheelEvent(ev as WheelEvent);
+          if (lines === 0) {
+            return false;
+          }
           action = deltaY < 0 ? CoreMouseAction.UP : CoreMouseAction.DOWN;
           but = CoreMouseButton.WHEEL;
           break;
@@ -817,6 +821,11 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           return false;
         }
 
+        const lines = self._consumeWheelEvent(ev as WheelEvent);
+        if (lines === 0) {
+          return false;
+        }
+
         // Construct and send sequences
         const sequence = C0.ESC + (this.coreService.decPrivateModes.applicationCursorKeys ? 'O' : '[') + (ev.deltaY < 0 ? 'A' : 'B');
         this.coreService.triggerDataEvent(sequence, true);
@@ -825,6 +834,38 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
     }, { passive: false }));
   }
 
+  // Stores a partial line amount when scrolling, this is used to keep track of how much of a line
+  // is scrolled so we can "scroll" over partial lines and feel natural on touchpads. This is a
+  // quick fix and could have a more robust solution in place that reset the value when needed.
+  private _wheelPartialScroll: number = 0;
+
+  /**
+   * Gets the number of pixels scrolled by the mouse event taking into account what type of delta
+   * is being used.
+   * @param ev The mouse wheel event.
+   */
+  private _consumeWheelEvent(ev: WheelEvent): number {
+    // Do nothing if it's not a vertical scroll event
+    if (ev.deltaY === 0 || ev.shiftKey) {
+      return 0;
+    }
+
+    if (!this._coreBrowserService || !this._renderService) {
+      return 0;
+    }
+    // Fallback to WheelEvent.DOM_DELTA_LINE
+    const targetWheelEventPixels = this._renderService.dimensions.device.cell.height / this._coreBrowserService.dpr;
+    let amount = 1;
+    if (ev.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
+      amount /= targetWheelEventPixels + 0.0; // Prevent integer division
+      this._wheelPartialScroll += amount;
+      amount = Math.floor(Math.abs(this._wheelPartialScroll)) * (this._wheelPartialScroll > 0 ? 1 : -1);
+      this._wheelPartialScroll %= 1;
+    } else if (ev.deltaMode === WheelEvent.DOM_DELTA_PAGE) {
+      amount *= this._bufferService.rows;
+    }
+    return amount;
+  }
 
   /**
    * Tells the renderer to refresh terminal content between two rows (inclusive) at the next

From ebddd5d3465b63aaae8379484694ef4a012db4f7 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Thu, 28 Aug 2025 22:54:50 -0700
Subject: [PATCH 02/12] Move from CoreBrowerTerminal to CoreMouseService. Still
 slow though

---
 src/browser/CoreBrowserTerminal.ts      | 43 ++++++-------------------
 src/common/TestUtils.test.ts            |  3 ++
 src/common/services/CoreMouseService.ts | 30 +++++++++++++++++
 src/common/services/Services.ts         |  5 +++
 4 files changed, 48 insertions(+), 33 deletions(-)

diff --git a/src/browser/CoreBrowserTerminal.ts b/src/browser/CoreBrowserTerminal.ts
index 37b33f7e..6ba27b66 100644
--- a/src/browser/CoreBrowserTerminal.ts
+++ b/src/browser/CoreBrowserTerminal.ts
@@ -646,7 +646,11 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           if (deltaY === 0) {
             return false;
           }
-          const lines = self._consumeWheelEvent(ev as WheelEvent);
+          const lines = self.coreMouseService.consumeWhellEvent(
+            ev as WheelEvent,
+            self._renderService?.dimensions?.device?.cell?.height,
+            self._coreBrowserService?.dpr
+          );
           if (lines === 0) {
             return false;
           }
@@ -821,7 +825,11 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           return false;
         }
 
-        const lines = self._consumeWheelEvent(ev as WheelEvent);
+        const lines = self.coreMouseService.consumeWhellEvent(
+          ev as WheelEvent,
+          self._renderService?.dimensions?.device?.cell?.height,
+          self._coreBrowserService?.dpr
+        );
         if (lines === 0) {
           return false;
         }
@@ -834,38 +842,7 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
     }, { passive: false }));
   }
 
-  // Stores a partial line amount when scrolling, this is used to keep track of how much of a line
-  // is scrolled so we can "scroll" over partial lines and feel natural on touchpads. This is a
-  // quick fix and could have a more robust solution in place that reset the value when needed.
-  private _wheelPartialScroll: number = 0;
 
-  /**
-   * Gets the number of pixels scrolled by the mouse event taking into account what type of delta
-   * is being used.
-   * @param ev The mouse wheel event.
-   */
-  private _consumeWheelEvent(ev: WheelEvent): number {
-    // Do nothing if it's not a vertical scroll event
-    if (ev.deltaY === 0 || ev.shiftKey) {
-      return 0;
-    }
-
-    if (!this._coreBrowserService || !this._renderService) {
-      return 0;
-    }
-    // Fallback to WheelEvent.DOM_DELTA_LINE
-    const targetWheelEventPixels = this._renderService.dimensions.device.cell.height / this._coreBrowserService.dpr;
-    let amount = 1;
-    if (ev.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
-      amount /= targetWheelEventPixels + 0.0; // Prevent integer division
-      this._wheelPartialScroll += amount;
-      amount = Math.floor(Math.abs(this._wheelPartialScroll)) * (this._wheelPartialScroll > 0 ? 1 : -1);
-      this._wheelPartialScroll %= 1;
-    } else if (ev.deltaMode === WheelEvent.DOM_DELTA_PAGE) {
-      amount *= this._bufferService.rows;
-    }
-    return amount;
-  }
 
   /**
    * Tells the renderer to refresh terminal content between two rows (inclusive) at the next
diff --git a/src/common/TestUtils.test.ts b/src/common/TestUtils.test.ts
index 127e1f24..b25a2182 100644
--- a/src/common/TestUtils.test.ts
+++ b/src/common/TestUtils.test.ts
@@ -66,6 +66,9 @@ export class MockCoreMouseService implements ICoreMouseService {
   public explainEvents(events: CoreMouseEventType): { [event: string]: boolean } {
     throw new Error('Method not implemented.');
   }
+  public consumeWhellEvent(ev: WheelEvent, cellHeight: number, dpr: number): number {
+    return 1; // Return a simple mock value
+  }
 }
 
 export class MockCharsetService implements ICharsetService {
diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index f2f02379..a1135a8a 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -174,6 +174,7 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
   private _activeProtocol: string = '';
   private _activeEncoding: string = '';
   private _lastEvent: ICoreMouseEvent | null = null;
+  private _wheelPartialScroll: number = 0;
 
   private readonly _onProtocolChange = this._register(new Emitter<CoreMouseEventType>());
   public readonly onProtocolChange =  this._onProtocolChange.event;
@@ -229,6 +230,35 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
     this.activeProtocol = 'NONE';
     this.activeEncoding = 'DEFAULT';
     this._lastEvent = null;
+    this._wheelPartialScroll = 0;
+  }
+
+  /**
+   * Processes a wheel event, accounting for partial scrolls for trackpad, mouse scrolls.
+   * This prevents hyper-sensitive scrolling in alt buffer.
+   */
+  public consumeWhellEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number {
+    // Do nothing if it's not a vertical scroll event
+    if (ev.deltaY === 0 || ev.shiftKey) {
+      return 0;
+    }
+
+    if (cellHeight === undefined || dpr === undefined) {
+      return 0;
+    }
+
+    // Fallback to WheelEvent.DOM_DELTA_LINE
+    const targetWheelEventPixels = cellHeight / dpr;
+    let amount = 1;
+    if (ev.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
+      amount /= targetWheelEventPixels + 0.0; // Prevent integer division
+      this._wheelPartialScroll += amount;
+      amount = Math.floor(Math.abs(this._wheelPartialScroll)) * (this._wheelPartialScroll > 0 ? 1 : -1);
+      this._wheelPartialScroll %= 1;
+    } else if (ev.deltaMode === WheelEvent.DOM_DELTA_PAGE) {
+      amount *= this._bufferService.rows;
+    }
+    return amount;
   }
 
   /**
diff --git a/src/common/services/Services.ts b/src/common/services/Services.ts
index 9c3aebf7..e7ccc241 100644
--- a/src/common/services/Services.ts
+++ b/src/common/services/Services.ts
@@ -58,6 +58,11 @@ export interface ICoreMouseService {
    * Human readable version of mouse events.
    */
   explainEvents(events: CoreMouseEventType): { [event: string]: boolean };
+
+  /**
+   * Process wheel event taking partial scroll into account.
+   */
+  consumeWhellEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number;
 }
 
 export const ICoreService = createDecorator<ICoreService>('CoreService');

From b104a5b953a22329917b5d22378465279e5b9eaf Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Thu, 28 Aug 2025 22:56:15 -0700
Subject: [PATCH 03/12] Respect original formatting

---
 src/browser/CoreBrowserTerminal.ts | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/browser/CoreBrowserTerminal.ts b/src/browser/CoreBrowserTerminal.ts
index 6ba27b66..bd513573 100644
--- a/src/browser/CoreBrowserTerminal.ts
+++ b/src/browser/CoreBrowserTerminal.ts
@@ -843,7 +843,6 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
   }
 
 
-
   /**
    * Tells the renderer to refresh terminal content between two rows (inclusive) at the next
    * opportunity.

From 26ecba8de1f5205c8a8f577c4ebce687ac23be84 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Mon, 8 Sep 2025 21:03:05 -0700
Subject: [PATCH 04/12] Fix sluggish mouse problem. Now similar to trackpad

---
 src/browser/CoreBrowserTerminal.ts      | 4 ++--
 src/common/TestUtils.test.ts            | 2 +-
 src/common/services/CoreMouseService.ts | 5 +++--
 src/common/services/Services.ts         | 2 +-
 4 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/browser/CoreBrowserTerminal.ts b/src/browser/CoreBrowserTerminal.ts
index bd513573..c9349760 100644
--- a/src/browser/CoreBrowserTerminal.ts
+++ b/src/browser/CoreBrowserTerminal.ts
@@ -646,7 +646,7 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           if (deltaY === 0) {
             return false;
           }
-          const lines = self.coreMouseService.consumeWhellEvent(
+          const lines = self.coreMouseService.consumeWheelEvent(
             ev as WheelEvent,
             self._renderService?.dimensions?.device?.cell?.height,
             self._coreBrowserService?.dpr
@@ -825,7 +825,7 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           return false;
         }
 
-        const lines = self.coreMouseService.consumeWhellEvent(
+        const lines = self.coreMouseService.consumeWheelEvent(
           ev as WheelEvent,
           self._renderService?.dimensions?.device?.cell?.height,
           self._coreBrowserService?.dpr
diff --git a/src/common/TestUtils.test.ts b/src/common/TestUtils.test.ts
index b25a2182..1ee79e75 100644
--- a/src/common/TestUtils.test.ts
+++ b/src/common/TestUtils.test.ts
@@ -66,7 +66,7 @@ export class MockCoreMouseService implements ICoreMouseService {
   public explainEvents(events: CoreMouseEventType): { [event: string]: boolean } {
     throw new Error('Method not implemented.');
   }
-  public consumeWhellEvent(ev: WheelEvent, cellHeight: number, dpr: number): number {
+  public consumeWheelEvent(ev: WheelEvent, cellHeight: number, dpr: number): number {
     return 1; // Return a simple mock value
   }
 }
diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index a1135a8a..7f3d5f39 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -237,7 +237,7 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
    * Processes a wheel event, accounting for partial scrolls for trackpad, mouse scrolls.
    * This prevents hyper-sensitive scrolling in alt buffer.
    */
-  public consumeWhellEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number {
+  public consumeWheelEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number {
     // Do nothing if it's not a vertical scroll event
     if (ev.deltaY === 0 || ev.shiftKey) {
       return 0;
@@ -251,7 +251,8 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
     const targetWheelEventPixels = cellHeight / dpr;
     let amount = 1;
     if (ev.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
-      amount /= targetWheelEventPixels + 0.0; // Prevent integer division
+      const pixelAmount = ev.deltaY;
+      amount = pixelAmount / (targetWheelEventPixels + 0.0); // Prevent integer division
       this._wheelPartialScroll += amount;
       amount = Math.floor(Math.abs(this._wheelPartialScroll)) * (this._wheelPartialScroll > 0 ? 1 : -1);
       this._wheelPartialScroll %= 1;
diff --git a/src/common/services/Services.ts b/src/common/services/Services.ts
index e7ccc241..d47c3bbc 100644
--- a/src/common/services/Services.ts
+++ b/src/common/services/Services.ts
@@ -62,7 +62,7 @@ export interface ICoreMouseService {
   /**
    * Process wheel event taking partial scroll into account.
    */
-  consumeWhellEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number;
+  consumeWheelEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number;
 }
 
 export const ICoreService = createDecorator<ICoreService>('CoreService');

From 50df7a69e61a6e49ec8c082231339bbb40bbc026 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Mon, 8 Sep 2025 21:06:37 -0700
Subject: [PATCH 05/12] remove unused var

---
 src/common/services/CoreMouseService.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index 7f3d5f39..bf01d73c 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -251,8 +251,7 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
     const targetWheelEventPixels = cellHeight / dpr;
     let amount = 1;
     if (ev.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
-      const pixelAmount = ev.deltaY;
-      amount = pixelAmount / (targetWheelEventPixels + 0.0); // Prevent integer division
+      amount = ev.deltaY / (targetWheelEventPixels + 0.0); // Prevent integer division
       this._wheelPartialScroll += amount;
       amount = Math.floor(Math.abs(this._wheelPartialScroll)) * (this._wheelPartialScroll > 0 ? 1 : -1);
       this._wheelPartialScroll %= 1;

From d862c823861ce04ef304bec2b1f028f69e3c98da Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Mon, 8 Sep 2025 21:14:20 -0700
Subject: [PATCH 06/12] no stale comments

---
 src/common/TestUtils.test.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/common/TestUtils.test.ts b/src/common/TestUtils.test.ts
index 1ee79e75..499fb787 100644
--- a/src/common/TestUtils.test.ts
+++ b/src/common/TestUtils.test.ts
@@ -67,7 +67,7 @@ export class MockCoreMouseService implements ICoreMouseService {
     throw new Error('Method not implemented.');
   }
   public consumeWheelEvent(ev: WheelEvent, cellHeight: number, dpr: number): number {
-    return 1; // Return a simple mock value
+    return 1;
   }
 }
 

From cf6b868dfbf1f10885e53b3c841f188ff3204037 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 9 Sep 2025 11:51:27 -0700
Subject: [PATCH 07/12] fastScrollModifier seems deprecated

---
 src/common/services/CoreMouseService.ts | 31 +++++++++++++++++++++----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index bf01d73c..e777f007 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -2,7 +2,7 @@
  * Copyright (c) 2019 The xterm.js authors. All rights reserved.
  * @license MIT
  */
-import { IBufferService, ICoreService, ICoreMouseService } from 'common/services/Services';
+import { IBufferService, ICoreService, ICoreMouseService, IOptionsService } from 'common/services/Services';
 import { ICoreMouseProtocol, ICoreMouseEvent, CoreMouseEncoding, CoreMouseEventType, CoreMouseButton, CoreMouseAction } from 'common/Types';
 import { Disposable } from 'vs/base/common/lifecycle';
 import { Emitter } from 'vs/base/common/event';
@@ -181,7 +181,8 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
 
   constructor(
     @IBufferService private readonly _bufferService: IBufferService,
-    @ICoreService private readonly _coreService: ICoreService
+    @ICoreService private readonly _coreService: ICoreService,
+    @IOptionsService private readonly _optionsService: IOptionsService
   ) {
     super();
     // register default protocols and encodings
@@ -247,11 +248,17 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
       return 0;
     }
 
-    // Fallback to WheelEvent.DOM_DELTA_LINE
     const targetWheelEventPixels = cellHeight / dpr;
-    let amount = 1;
+    let amount = this._applyScrollModifier(ev.deltaY, ev);
+
     if (ev.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
-      amount = ev.deltaY / (targetWheelEventPixels + 0.0); // Prevent integer division
+      amount /= (targetWheelEventPixels + 0.0); // Prevent integer division
+
+      const isLikelyTrackpad = Math.abs(ev.deltaY) < 50;
+      if (isLikelyTrackpad) {
+        amount *= 0.3;
+      }
+
       this._wheelPartialScroll += amount;
       amount = Math.floor(Math.abs(this._wheelPartialScroll)) * (this._wheelPartialScroll > 0 ? 1 : -1);
       this._wheelPartialScroll %= 1;
@@ -261,6 +268,20 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
     return amount;
   }
 
+  private _applyScrollModifier(amount: number, ev: WheelEvent): number {
+    const modifier = this._optionsService.rawOptions.fastScrollModifier; // QUESTION: This is always alt. Seems deprecated via: https://github.com/xtermjs/xterm.js/blob/5.5.0/src/browser/Viewport.ts
+    console.log('what is this modifier: ', modifier);
+
+    // Multiply the scroll speed when the modifier key is pressed
+    if ((modifier === 'alt' && ev.altKey) ||
+        (modifier === 'ctrl' && ev.ctrlKey) ||
+        (modifier === 'shift' && ev.shiftKey)) {
+      return amount * this._optionsService.rawOptions.fastScrollSensitivity * this._optionsService.rawOptions.scrollSensitivity;
+    }
+
+    return amount * this._optionsService.rawOptions.scrollSensitivity;
+  }
+
   /**
    * Triggers a mouse event to be sent.
    *

From 03ce26c6975ad2f71276a87e984bf9bec0503db5 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 9 Sep 2025 11:56:28 -0700
Subject: [PATCH 08/12] Questions, possible concern

---
 src/common/services/CoreMouseService.ts | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index e777f007..da94ed97 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -177,7 +177,7 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
   private _wheelPartialScroll: number = 0;
 
   private readonly _onProtocolChange = this._register(new Emitter<CoreMouseEventType>());
-  public readonly onProtocolChange =  this._onProtocolChange.event;
+  public readonly onProtocolChange = this._onProtocolChange.event;
 
   constructor(
     @IBufferService private readonly _bufferService: IBufferService,
@@ -270,12 +270,16 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
 
   private _applyScrollModifier(amount: number, ev: WheelEvent): number {
     const modifier = this._optionsService.rawOptions.fastScrollModifier; // QUESTION: This is always alt. Seems deprecated via: https://github.com/xtermjs/xterm.js/blob/5.5.0/src/browser/Viewport.ts
-    console.log('what is this modifier: ', modifier);
+    // Problem is that modifier always seem 'alt' even when ev.ctrlKey is true, for example.
+    // Maybe this doesnt matter because all of alt, ctrl, shift does same operation?
 
     // Multiply the scroll speed when the modifier key is pressed
     if ((modifier === 'alt' && ev.altKey) ||
-        (modifier === 'ctrl' && ev.ctrlKey) ||
-        (modifier === 'shift' && ev.shiftKey)) {
+      (modifier === 'ctrl' && ev.ctrlKey) ||
+      (modifier === 'shift' && ev.shiftKey)) {
+
+      console.log('fast scroll sensitivity: ', this._optionsService.rawOptions.fastScrollSensitivity);
+      console.log('regular scroll sensitivity: ', this._optionsService.rawOptions.scrollSensitivity);
       return amount * this._optionsService.rawOptions.fastScrollSensitivity * this._optionsService.rawOptions.scrollSensitivity;
     }
 

From 1a6a807f6816de4d14a5138817afa8dcc5df595d Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 9 Sep 2025 11:59:29 -0700
Subject: [PATCH 09/12] Remove stale comment

---
 src/common/services/CoreMouseService.ts | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index da94ed97..99cd1fc5 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -278,8 +278,6 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
       (modifier === 'ctrl' && ev.ctrlKey) ||
       (modifier === 'shift' && ev.shiftKey)) {
 
-      console.log('fast scroll sensitivity: ', this._optionsService.rawOptions.fastScrollSensitivity);
-      console.log('regular scroll sensitivity: ', this._optionsService.rawOptions.scrollSensitivity);
       return amount * this._optionsService.rawOptions.fastScrollSensitivity * this._optionsService.rawOptions.scrollSensitivity;
     }
 

From 38bee71630a4680cb86b1df00adfd1b9a28973c7 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 9 Sep 2025 12:00:19 -0700
Subject: [PATCH 10/12] More clear comments

---
 src/common/services/CoreMouseService.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index 99cd1fc5..9b74daeb 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -271,7 +271,7 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
   private _applyScrollModifier(amount: number, ev: WheelEvent): number {
     const modifier = this._optionsService.rawOptions.fastScrollModifier; // QUESTION: This is always alt. Seems deprecated via: https://github.com/xtermjs/xterm.js/blob/5.5.0/src/browser/Viewport.ts
     // Problem is that modifier always seem 'alt' even when ev.ctrlKey is true, for example.
-    // Maybe this doesnt matter because all of alt, ctrl, shift does same operation?
+    // May need to tweak conditional to: if any of `ev.altKey || ev.ctrlKey || ev.shiftKey` is true
 
     // Multiply the scroll speed when the modifier key is pressed
     if ((modifier === 'alt' && ev.altKey) ||

From e4f222f6b00ed853895b154f65c86d0a2a742312 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 9 Sep 2025 12:03:51 -0700
Subject: [PATCH 11/12] Make test happy

---
 src/common/services/CoreMouseService.test.ts | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/common/services/CoreMouseService.test.ts b/src/common/services/CoreMouseService.test.ts
index 34710897..3b79596d 100644
--- a/src/common/services/CoreMouseService.test.ts
+++ b/src/common/services/CoreMouseService.test.ts
@@ -3,13 +3,14 @@
  * @license MIT
  */
 import { CoreMouseService } from 'common/services/CoreMouseService';
-import { MockCoreService, MockBufferService } from 'common/TestUtils.test';
+import { MockCoreService, MockBufferService, MockOptionsService } from 'common/TestUtils.test';
 import { assert } from 'chai';
 import { ICoreMouseEvent, CoreMouseEventType, CoreMouseButton, CoreMouseAction } from 'common/Types';
 
 // needed mock services
 const bufferService = new MockBufferService(300, 100);
 const coreService = new MockCoreService();
+const optionsService = new MockOptionsService();
 
 function toBytes(s: string | undefined): number[] {
   if (!s) {
@@ -24,20 +25,20 @@ function toBytes(s: string | undefined): number[] {
 
 describe('CoreMouseService', () => {
   it('init', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     assert.equal(cms.activeEncoding, 'DEFAULT');
     assert.equal(cms.activeProtocol, 'NONE');
   });
   it('default protocols - NONE, X10, VT200, DRAG, ANY', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     assert.deepEqual(Object.keys((cms as any)._protocols), ['NONE', 'X10', 'VT200', 'DRAG', 'ANY']);
   });
   it('default encodings - DEFAULT, SGR', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     assert.deepEqual(Object.keys((cms as any)._encodings), ['DEFAULT', 'SGR', 'SGR_PIXELS']);
   });
   it('protocol/encoding setter, reset', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     cms.activeEncoding = 'SGR';
     cms.activeProtocol = 'ANY';
     assert.equal(cms.activeEncoding, 'SGR');
@@ -49,19 +50,19 @@ describe('CoreMouseService', () => {
     assert.throws(() => { cms.activeProtocol = 'xyz'; }, 'unknown protocol "xyz"');
   });
   it('addEncoding', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     cms.addEncoding('XYZ', (e: ICoreMouseEvent) => '');
     cms.activeEncoding = 'XYZ';
     assert.equal(cms.activeEncoding, 'XYZ');
   });
   it('addProtocol', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     cms.addProtocol('XYZ', { events: CoreMouseEventType.NONE, restrict: (e: ICoreMouseEvent) => false });
     cms.activeProtocol = 'XYZ';
     assert.equal(cms.activeProtocol, 'XYZ');
   });
   it('onProtocolChange', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     const wantedEvents: CoreMouseEventType[] = [];
     cms.onProtocolChange(events => wantedEvents.push(events));
     cms.activeProtocol = 'NONE';
@@ -76,7 +77,7 @@ describe('CoreMouseService', () => {
     let cms: CoreMouseService;
     let reports: string[];
     beforeEach(() => {
-      cms = new CoreMouseService(bufferService, coreService);
+      cms = new CoreMouseService(bufferService, coreService, optionsService);
       reports = [];
       coreService.triggerDataEvent = (data: string, userInput?: boolean) => reports.push(data);
       coreService.triggerBinaryEvent = (data: string) => reports.push(data);

From 9c42fb348b38a9fa7a1cc817edcb63059652dfc0 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 9 Sep 2025 13:21:37 -0700
Subject: [PATCH 12/12] ignore fastScrollModifier

---
 src/common/services/CoreMouseService.ts | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index 9b74daeb..a10ddafb 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -269,18 +269,10 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
   }
 
   private _applyScrollModifier(amount: number, ev: WheelEvent): number {
-    const modifier = this._optionsService.rawOptions.fastScrollModifier; // QUESTION: This is always alt. Seems deprecated via: https://github.com/xtermjs/xterm.js/blob/5.5.0/src/browser/Viewport.ts
-    // Problem is that modifier always seem 'alt' even when ev.ctrlKey is true, for example.
-    // May need to tweak conditional to: if any of `ev.altKey || ev.ctrlKey || ev.shiftKey` is true
-
     // Multiply the scroll speed when the modifier key is pressed
-    if ((modifier === 'alt' && ev.altKey) ||
-      (modifier === 'ctrl' && ev.ctrlKey) ||
-      (modifier === 'shift' && ev.shiftKey)) {
-
+    if (ev.altKey || ev.ctrlKey || ev.shiftKey) {
       return amount * this._optionsService.rawOptions.fastScrollSensitivity * this._optionsService.rawOptions.scrollSensitivity;
     }
-
     return amount * this._optionsService.rawOptions.scrollSensitivity;
   }