Fix notebook scrolling in web mode#13558
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In web-hosted Positron, the monaco-workbench element's wheel event listener calls preventDefault() during the bubble phase, which blocks native scrolling on the notebook cells container. In Electron this doesn't occur because the workbench's ScrollableElement short-circuits when it has nothing to scroll. Add stopPropagation() on wheel events at the cells container so they never reach the workbench handler, restoring native overflow:auto scrolling in web mode.
Explain why the handler runs unconditionally (harmless in Electron) and why the empty dependency array is safe (container DOM node is stable for the component lifetime).
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E2E Tests 🚀 |
The previous comment incorrectly attributed the behavior to a ScrollableElement short-circuit. The real cause is BrowserWindow (window.ts:271) registering an unconditional preventDefault() on all wheel events on mainContainer to block macOS back/forward gestures. This listener only exists in the web build; NativeWindow (Electron) has no wheel handler at all.
dhruvisompura
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May 14, 2026
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Fix worked for me on a web build!
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In web-hosted Positron the workbench's
monaco-scrollable-elementancestor callspreventDefault()on wheel events during the bubble phase, which blocks native scrolling on the notebook cells container. In Electron this doesn't manifest because the workbench'sScrollableElementshort-circuits when it detects it has nothing to scroll.This PR fixes this by adding a
stopPropagation()on wheel events at the cells container boundary so they never reach the workbench handler, restoring nativeoverflow: autoscrolling in web mode. Applied unconditionally since it's harmless in Electron (the ancestor already skipspreventDefaultwhen it has no overflow).References
Root cause:
src/vs/workbench/browser/window.ts:271-- theBrowserWindowwheel listener that callspreventDefault()on all wheel events onmainContainer. Only exists in web build.src/vs/workbench/electron-browser/window.ts:84--NativeWindow(Electron equivalent) has no wheel handler, which is why this only affects web mode.Why CSS alone can't fix it:
src/vs/workbench/browser/media/style.css:70-73--.monaco-workbench.webalready hasoverscroll-behavior: none, but that only prevents scroll-chaining, notpreventDefault()canceling native scroll.The fix (stopPropagation pattern):
src/vs/workbench/contrib/positronNotebook/browser/PositronNotebookComponent.tsx:106-119-- the fix itselfsrc/vs/workbench/contrib/positronConnections/browser/components/newConnectionModalDialog/createConnectionState.tsx:190-196-- same pattern already in use for the same reason, with a comment linking to the root causeScroll mechanics for context:
src/vs/base/browser/ui/scrollbar/scrollableElement.ts:424-- ScrollableElement registers with{ passive: false }(same mechanism the workbench listener uses to block scrolling)src/vs/workbench/contrib/positronNotebook/browser/PositronNotebookComponent.css:101-- the cells container uses nativeoverflow: autoRelease Notes
New Features
Bug Fixes
Validation Steps
@:positron-notebooks @:web