The overlap crosshair sat on the pair's area centroid. For a split,
holed or concave overlap, that point can be off the red material:
between two patches, in a hole, or inside a curve.
PlateOverlapPair.Marker is a point inside the pair's largest island.
It is the island's pole of inaccessibility (PolyLabel), searched to a
tenth of the island's area/perimeter within a 4096-cell budget. If
that bounded search does not land inside (a long thin sliver), the
marker falls back to the midpoint of the widest interior run of a
horizontal scan line placed between vertex heights.
The overlay crosshair, marker hit testing, hover coordinates
("Marker:") and the cutting-inspection ring now use the marker.
Centroid stays the true area centroid. View > Overlap Check > Display
> Centroids is now labelled Markers.
Before the marker existed, its call sites used the centroid. Two
patches, a covered frame, a half annulus and a thin crescent then put
it off the material; now all four land on it. Disabling the scan-line
fallback fails its test. On the 389-plate corpus, markers add about
0.4 ms per overlapping pair; pair and area results are unchanged.
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