Subj : Syncarcade - odd graphics displaying in top left hand corner of screen
To   : GitLab note in main/sbbs
From : Rob Swindell
Date : Tue Aug 04 2026 15:13:53

https://gitlab.synchro.net/main/sbbs/-/issues/1214#note_9914

Thanks for the report, and for the video -- that made this quick to pin down.

The cause is on our side, not SyncTERM's. The door asks the terminal to draw
sixel images at the text cursor, via DEC private mode 80 (DECSDM). CTerm
reversed that mode's set/reset sense in revision 1.328 (2026-06-28), and
SyncTERM 1.8 ships CTerm 1.327 -- one revision earlier. So the sequence the
door sends means the opposite of what it intends on 1.8: the terminal ignores
the cursor and anchors every image at the top-left corner of the screen.

That is exactly what your video shows. The game picture itself lands top-left
instead of centered, and -- more visibly -- the small partial updates the door
sends between full frames (it repaints only the cells that changed, to save
bandwidth) all pile into that same corner instead of landing over the part of
the screen they belong to. Hence the block of scrambled graphics that keeps
changing up there while the game plays on below it.

The doors now read the CTerm revision out of the terminal's device-attributes
reply and send whichever of the two sequences that particular build reads as
"draw at the cursor", so old and new SyncTERM are both handled. The same
assumption was baked into SyncDOOM, SyncDuke, SyncMOO1, SyncSCUMM and SyncRPG,
so all of them got the fix too.

Could you retest on cvs.synchro.net? The fixed Linux build of the door is
running there now. vert.synchro.net serves the Windows build from the same
directory, and that one has not been rebuilt yet, so vert will still show the
problem.

Please stay on SyncTERM 1.8 for the retest -- 1.8 is the case being fixed, so
it is the useful one to confirm. What you should see: no scrambled graphics in
the top-left, and the game picture centered in the window rather than pushed
against the left edge.

The change is not committed or released yet. It is deployed on cvs.synchro.net
precisely so it can be confirmed against a real 1.8 client first.

-- *Authored by Claude (Claude Code), on behalf of @rswindell*
--- SBBSecho 3.37-Linux
 * Origin: Vertrauen - [vert/cvs/bbs].synchro.net (1:103/705)

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