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Remove will-change: width and use actual element height in PageLayout drag optimizations #7374

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Remove will-change: width and use actual element height in PageLayout drag optimizations #7374

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Copilot Dec 26, 2025
ef70170
Remove will-change: width and use actual element height in paneUtils
Copilot Dec 26, 2025
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8 changes: 4 additions & 4 deletions packages/react/src/PageLayout/PageLayout.test.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -234,7 +234,7 @@ describe('PageLayout', async () => {
expect(content!.style.getPropertyValue('contain')).toBe('')
})

it('should add will-change during drag for optimized updates', async () => {
it('should not add will-change during drag', async () => {
const {container} = render(
<PageLayout>
<PageLayout.Pane resizable>
Expand All @@ -252,10 +252,10 @@ describe('PageLayout', async () => {
// Before drag - no will-change
expect(pane!.style.willChange).toBe('')

// Start drag - will-change is added
// Start drag - will-change should still not be set (removed optimization)
fireEvent.pointerDown(divider, {clientX: 300, clientY: 200, pointerId: 1})
expect(pane!.style.willChange).toBe('width')
// End drag - will-change is removed
expect(pane!.style.willChange).toBe('')
// End drag - will-change remains unset
fireEvent.lostPointerCapture(divider, {pointerId: 1})
expect(pane!.style.willChange).toBe('')
})
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4 changes: 1 addition & 3 deletions packages/react/src/PageLayout/paneUtils.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ export function setContainmentOptimizations(element: HTMLElement | null) {
if (!element) return
element.style.contain = 'layout style paint'
element.style.contentVisibility = 'auto'
element.style.containIntrinsicSize = 'auto 500px'
element.style.containIntrinsicSize = `auto ${element.offsetHeight}px`
element.style.pointerEvents = 'none'
}

Expand All @@ -36,7 +36,6 @@ export function setDraggingStyles({handle, pane, content}: DraggingStylesParams)
handle?.style.setProperty('--draggable-handle--drag-opacity', '1')
// Disable transition for instant visual feedback during drag
handle?.style.setProperty('--draggable-handle--transition', 'none')
pane?.style.setProperty('will-change', 'width')
setContainmentOptimizations(content)
setContainmentOptimizations(pane)
}
Expand All @@ -46,7 +45,6 @@ export function removeDraggingStyles({handle, pane, content}: DraggingStylesPara
handle?.style.removeProperty('background-color')
handle?.style.removeProperty('--draggable-handle--drag-opacity')
handle?.style.removeProperty('--draggable-handle--transition')
pane?.style.removeProperty('will-change')
removeContainmentOptimizations(content)
removeContainmentOptimizations(pane)
}