Fix editor scroll jumping randomly after window refocus (#28795)

[jing11223344]

This PR fixes issue #28795 where the VS Code editor scrolls to random positions after switching back from another window (browser, terminal, etc.).

Root Cause

Chromium/Electron accumulates wheel scroll events while the VS Code window is not focused. When the window regains focus, these stale accumulated events are replayed all at once, causing the editor to jump.

Fix

In , track the last wheel event timestamp and the last window focus time. When a wheel event arrives after a gap of >400ms and the window was refocused during that gap, the event is identified as a replayed stale event and discarded.

Testing

• Reproduce old behavior: scroll heavily in a browser, alt-tab to VS Code, scroll once → editor jumps
• With fix: scroll events accumulated while unfocused are discarded on refocus
• Normal scrolling behavior is unaffected (events arriving within 400ms of each other pass through normally)

Fixes #28795

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Mitigates random editor scroll jumps after refocusing the window by filtering out wheel events that Chromium/Electron may replay after focus is regained.

Changes:

• Track last processed wheel-event time and last window-focus time on AbstractScrollableElement.
• Add a window focus listener to record refocus time.
• Discard wheel events deemed “stale replay” based on a >400ms gap combined with a refocus during that gap.

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