[TabScrollButton] Fix StartScrollButtonIcon/EndScrollButtonIcon swap in RTL#48502
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starboyvarun wants to merge 1 commit intomui:masterfrom
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[TabScrollButton] Fix StartScrollButtonIcon/EndScrollButtonIcon swap in RTL#48502starboyvarun wants to merge 1 commit intomui:masterfrom
starboyvarun wants to merge 1 commit intomui:masterfrom
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…in RTL (mui#39296) In RTL layout, Tabs.js passes `direction=right` to the start scroll button and `direction=left` to the end scroll button (flipped from LTR). However, TabScrollButton chose which slot icon to render based solely on `direction`, without accounting for the RTL flip. This caused custom `StartScrollButtonIcon` and `EndScrollButtonIcon` slot overrides to appear on the wrong sides in RTL. Fix: use `(direction === left) !== isRtl` to select the icon slot so that in RTL the semantic start/end mapping follows the visual flip applied by Tabs.
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mj12albert
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May 8, 2026
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This breaks vertical orientation
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Summary
Fixes #39296.
In RTL layout,
Tabs.jspassesdirection="right"to the start scroll button anddirection="left"to the end scroll button (the directions are flipped so the arrows point the right way visually). However,TabScrollButtonselected which slot icon to render based solely ondirection === 'left'with no awareness of RTL. This caused customStartScrollButtonIconandEndScrollButtonIconslot overrides to appear on the wrong sides in RTL mode.Fix: Change the icon selection to
(direction === 'left') !== isRtl. This XOR keeps LTR behavior identical and inverts the slot mapping in RTL soStartScrollButtonIconalways renders in the start scroll button andEndScrollButtonIconalways renders in the end scroll button, regardless of direction.Test plan
StartScrollButtonIconrenders fordirection="right"in RTLEndScrollButtonIconrenders fordirection="left"in RTL