Do not use visual children enumerator in TopLevelHost#21048
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MrJul merged 2 commits intoMar 31, 2026
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MrJul
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You can test this PR using the following package version. |
kekekeks
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Mar 31, 2026
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What does the pull request do?
This PR fixes an issue where if children are added to
TopLevelHostdynamically while a measure pass is in progress, anInvalidOperationException: Collection was modified; enumeration operation may not executeis thrown.This happens, for example, by setting
Window.ExtendClientAreaToDecorationsHint = trueinOnAttachedToVisualTree.This is a general problem with the visual and logical children collection, and a solution such as #20028 will be implemented in the future.
In the meantime, change
TopLevelHostto iterate using a plain oldforloop, matching what's done inMeasureOverride/ArrangeOverridefor all other controls.