Deadlock on focus events with invisible window,#3534

Editor assessment

Several small defects cluster in this header: 'deadlock on focus events with invisible window,#3534' is a noun phrase rather than an imperative statement ('Fix deadlock on focus events…'), there is a missing space before '#3534', and the issue reference is dumped without a 'closes' keyword, weakening forge-side auto-linking semantics. The core scope is correct and the described defect — a deadlock — is unmistakably a fix, so the type is right. No body: deadlocks are notoriously subtle, so even one sentence about the lock ordering or event-loop reentrancy involved would be valuable history. All fixable; as written it is a scruffy fix header, though still parseable by most tooling.