I have two wide monitors.  The "main" monitor is landscape, and the
"secondary" monitor (located to the right) is portrait.  The workspace
preview applet, that I have in a panel, doesn't show the whole
workspaces.  Attached is a screenshot displaying the problems.  I placed
four windows at the four corners of the main monitor, one in the upper
half of the secondary monitor and one in the lower half.  You'll notice
that only a sliver of the lower windows of the main monitor are visible
in the applet, and that the window in the lower half of the secondary
monitor is completely hidden.

  Thanks,

Roland.

Hi Roland,

this was fixed upstream in commit 2fcca119a ("Workspace switcher applet:
various improvements to the graph style", PR #8352), first released in
Cinnamon 4.2.0.

Up to Cinnamon 2.8 the workspace graph set its drawing area to a size
computed from the panel height in the constructor, then recomputed it
with different values at repaint time, and scaled the windows without
subtracting the work area origin. The drawing surface did not match the
actual allocation, so the bottom part of the graph was clipped; the
mismatch grew the further the aspect ratio of the combined monitor area
was from a single screen, which is exactly the case with a portrait
monitor next to a landscape one. Since 4.2.0 the graph size and the
scale factor are derived once from the work area of all monitors and
from the panel height minus the real theme padding and borders, and
window rectangles are offset by the work area origin.

In Debian the fix is available since cinnamon 4.2.4-2, so I am closing
this bug. Please reopen if you still see it with the version in
unstable (6.6.9-2).

Thanks for the report.