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Fixed in 2020.2.X

Fixed in 2020.1.X



Found in


Issue ID




[IMGUI] Assertion failed errors when docking an editor window containing a GUILayout.window

Window management


1. Create a new project.
2. Install ProBuilder through the package manager.
3. Open the ProBuilder window. (Tools -> ProBuilder -> ProBuilder Window)
4. Open the UV Editor window. (ProBuilder Window -> UV Editor)
5. Dock the UV Editor window anywhere.

Expected Outcome: No issues, no errors.
Actual Outcome: Continuous errors in the console.

Reproducible in 2020.1.0a22 with ProBuilder preview.2 4.3.0, 4.1.0. Doesn't seem to be package specific.
Not reproducible in 2020.1.0a21 with ProBuilder preview.2 4.3.0

Error Message:
Assertion failed on expression: '!dest.m_MultiFrameGUIState.m_Windows'

- Tested on Windows and Mac.
- Errors can be cleared, but will continue to print to console until you restart the project.
- GIF attached demonstrating the issue.
- Tried other Probuilder windows, no apparent issues.
- Tried other dockable editor windows, no apparent issues. Unsure if there are any other windows affected by this.

  1. Resolution Note (fix version 2020.2):

    Fixed in 2020.2.0a1

  2. Resolution Note (fix version 2020.1):

    Fixed in 2020.1.0b1

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