Auto-scroll does not trigger when drag-selecting text near viewport edges

[blyzmaksim]

Type

• Bug

Description

When selecting text by clicking and dragging toward the top or bottom edge of the paginated document viewport, the editor does not auto-scroll to reveal more content. The user must manually scroll and then continue selecting, which breaks the natural text selection workflow.

Current Behavior

1. User clicks to start a text selection
2. User drags toward the bottom (or top) of the visible viewport
3. The selection extends only to the edge of the visible area
4. The viewport does not auto-scroll to reveal additional pages/content
5. Selection stops at the viewport boundary

Expected Behavior

1. User clicks to start a text selection
2. User drags toward the bottom (or top) of the visible viewport
3. As the mouse approaches the edge, the viewport should automatically scroll in that direction
4. The selection should continue extending as new content becomes visible

Steps to Reproduce

1. Initialize SuperDoc with pagination: true
2. Create or open a document with content spanning multiple pages
3. Scroll to the middle of the document
4. Hold the mouse button and drag downward toward the bottom edge of the viewport
5. Observe: The viewport does not scroll; selection stops at the visible boundary

SuperDoc Version

1.4

Browser & Version

Chrome 120

OS

macOS 15.5

Additional Context

No response

Checklist

• Tested with latest version
• Checked for duplicates
• Added relevant labels

[linear]

IT-267