[HIGH] [SDL #5128] SDL doesn't handle clipboard when MessageBox is shown

[Chevalier12]

Tracking upstream SDL issue libsdl-org#5128

• Priority: HIGH — provisional triage from SDL-OPEN-ISSUES-PRIORITIES.md, NOT an official SDL severity.
• Source: SDL doesn't handle clipboard when MessageBox is shown libsdl-org/SDL#5128
• Original title: SDL doesn't handle clipboard when MessageBox is shown
• Reported by: a1batross
• Upstream state at capture: open; state reason:
• Created: 2021-12-22T01:49:14.0000000Z; updated: 2023-11-07T04:00:02.0000000Z
• Snapshot captured: 2026-09-07T17:43:55.2173651Z
• Upstream labels:
• Upstream milestone (not affected versions): 3.x (https://github.com/libsdl-org/SDL/milestone/6)
• Upstream assignees:
• Upstream comments included: 0
• Locked: False; lock reason:
• Triage rationale: Blocare de evenimente/UI sau ANR raportat; verificați versiunea și scenariul înainte de fix.

This is an attributed tracking copy, not a locally reproduced or confirmed Graphix defect. Applicability, affected versions and ownership still require validation. No automatic synchronization or resolution is implied. Original descriptions and comments are preserved literally in Markdown code blocks to avoid notifying mentioned users or resolving SDL references against Graphix. Attachments, logs, patches and other linked resources remain at their original URLs; external resource contents and edit/event histories are not copied.

Graphix validation checklist

• Read the current upstream issue and discussion.
• Establish affected versions/platforms and whether Graphix is affected.
• Reproduce the reported behavior and identify the invariant owner.
• Implement an ownership-correct fix or document an upstream/external resolution.
• Verify regression coverage and applicable platform/runtime gates.

Original description

Hello!

I'm trying to implement pasting game engine error message into clipboard. I call SDL_ShowMessageBox with custom button, which calls SDL_SetClipboardText and then re-creates message box to pause and not shutdown the engine.

The main loop is blocked, all events is handled inside MessageBox X11 code which doesn't respond to clipboard copy, causing any X11 application that text was pasted into to freeze.

Sample program: https://gist.github.com/a1batross/a43442d4716d7eb079dffc95eadea5c1

I haven't tested this on other platforms that support message boxes.

Original discussion (chronological)