bug: overlay display artifact: trace left behind

[Drew Adams]

See attached image. The red traces are left behind by just moving a
one-character red overlay across the line (I removed the overlay at the
end). Clearing the display (`C-l') removes the trace, but it is still
annoying.

Notice that the trace is left only between certain pairs of characters, and
that doesn't seem to have to do with the appearance of the characters,
because lowercase and uppercase versions of the same letter act the same.
For instance, there is no trace between the `T' and `Y' in `WARRANTY', and
the same is true of the `t' and `y' in `warranty'.

I started with emacs -Q, and just repeatedly used a command that moved a
one-character overlay to the right one character.

I thought this might also be behind the problem I reported in thread
"two-pixel trace left when move overlay" (April 2006), but that problem
occurs only when `indent-tabs-mode' is nil. This new problem remains even if
I set `indent-tabs-mode' to t.


In GNU Emacs 22.0.50.1 (i386-msvc-nt5.1.2600)
 of 2006-07-19 on BOS-CTHEWLAP2
X server distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-msvc (12.00)'

bug-overlay-artifact.jpg
Description: JPEG image