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Fixed in Built-in



Found in [Package]


Issue ID




MouseEnterEvent is called multiple times when moving mouse over Slider

Package: UI Toolkit


How to reproduce:
1. Open the attached project ("")
2. Enter Play Mode
3. Mouse over the Slider area

Expected result: MouseEnterEvent event called once, Debug.Log for each parameter printed once in the Console
Actual result: MouseEnterEvent event called multiple times, Debug.Log printed multiple times in the Console

Reproducible with: 1.0.0-preview-15, 1.0.0-preview-18 (2020.3.20f1, 2021.1.25f1), Built-in (2021.2.0b16, 2022.1.0a12)
Could not test with: 2019.4.31f1 (UI Toolkit not available)

- Could not check older preview versions - "error CS0535: 'DefaultEditorWindowBackend' does not implement interface member 'IEditorWindowBackend.overlayGUIHandler'"
- Reproducible with old input system and Input System package
- MouseEnterEvent gets called 3 times when moused over the element's "margin" and then once more when moused over the slider portion of the element
- Also reproducible with Toggle
- Not reproducible with Label, EnumField

  1. Resolution Note (fix version Built-in):

    Fixed in: 2022.1.0a15

  2. Resolution Note (fix version Built-in):

    Fixed in: 2021.2.7f1

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