dotnet/winforms

FormClosed event is raised twice for owned modal window when owner window is closed programatically

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#2,451 opened on Nov 29, 2019

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:beetle: bughelp wanted

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Description

See attached sources. I can reproduce this issue with .Net Core 3.0 and .Net Framework 4.7.2

The second call to OnFormClosed() seems to be a side effect of shutting down the modal message loop that was created to run the child window.

BugFormClosedRaisedTwice.zip

Contributor guide

Research direction
Investigate the FormClosed event raising mechanism and the modal message loop shutdown in WinForms. Check if the issue is caused by calling Close() on the owner window, which triggers FormClosed on owned modal windows twice due to message loop termination.
Tech stack
csharp
Domain
desktop
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Gitcsharp
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75