TestAssemblySetup set the unhandled-exception mode and a ThreadException
handler from a module initializer. WinForms stores both per thread
(ThreadContext/NativeWindow thread statics), so they applied only to the
runner thread that loaded the assembly, never to the STA threads the
tests run on. There, an exception escaping a window message or a
BeginInvoke/SynchronizationContext callback still opened a modal
ThreadExceptionDialog in an interactive session, or was silently ignored
otherwise; the handler would also have logged and swallowed it.
Replace the fifteen copied RunSta helpers with StaTestThread.Run, which
selects UnhandledExceptionMode.ThrowException on each STA thread before
it creates a window, so the exception propagates to the test body and
fails the test. Each class keeps its own timeout and message; all
threads are now background threads. Remove TestAssemblySetup.
StaTestThreadTests covers a throwing BeginInvoke callback through
StaTestThread (fails with the original exception) and, as a control,
the default mode on a plain STA thread (the exception goes to the
thread's handler and never reaches the test body). Cross-compiled on
Linux; Windows execution is the windows-desktop CI job.
Nest windows now rerun the overlap check once the layout has been
unchanged for 0.5 s, instead of leaving 'Overlaps: not checked'. Edits
show 'Overlaps: check pending...'; drags are caught by the paint-time
pose stamp, collection edits by their events. The check waits while a
mouse button, modal dialog or fill is active, supersedes a running check
when the layout moves again, and does not retry a canceled or failed
layout until it changes. Rechecks use the incremental analyzer, so only
the moved parts' neighbors are recomputed.
Automatic results update only the canvas label (the status bar keeps the
last command's message) and keep Display > Off. Check Active Plate still
runs immediately. InvalidateOverlapCheck now also drops cached material.
aj