GQview 1.3.7-1.5.7 - buggy file refresh/image change interaction

Hello,

While previewing series of images while they are being downloaded,
I've noticed that occasionally, if a directory-refresh occurs at just
the right time when I'm switching from one image to another, the next
image will load up all black, and then the next flip-image operation
will skip either to the first image or, rarely, the last image in the
directory.  Usually the black in-between "image" doesn't show up at
all and the first image just suddenly pops up when I'm expecting the
next one in the series.  This is often simultaneous with the redrawing
of the image file list.  (Usually images are coming in to the end of
the directory listing in sort order at about 10-15 seconds/image; the
skip is to the beginning.) This is especially unhappy in directories
with hundreds or thousands of images where I don't know where I just
was.

The expected behavior would be to not skip; the next-image command
should move to the next image in the sort order as usual, regardless
of whether a file refresh is taking place at the time.

Reproducibility is a bit of an issue; I can't seem to trigger the skip
just by quickly scrolling up and down in the file list (using the
mouse wheel to flip images).  Casually skimming images at about 2
images/second seems to cause the problem maybe one out of about every
5 times that GQview refreshes the directory list due to a new
file being added.

The problem also occurs in full screen mode with smooth flip enabled.
I originally had thought that GQview must be somewhere in the preload
process during file refresh event, but it happens even with preload
disabled.

I've been noticing this for over a year, probably since GQview
switched from gtk lists to gtk-2 trees; perhaps this is the
culprit.  I've noticed during my testing that the file list refresh is
visibly noticeable in the treeview versions, whereas I couldn't see
any flicker at all in 1.3.2 or 1.1.6.

Versions tested:
----------------
1.5.7 (latest dev) - afflicted
1.4.5 (latest stable, Debian package) - also afflicted
1.3.7 (newly built, old dev version with GTK 2.0 support completed) -
    also afflicted
=====
1.3.2 (old compile pre-GtkTreeView partial GTK 2.0 port) - couldn't
    trigger the bug
1.1.6 (old compile from just after the directory refresh was
    implemented) - couldn't trigger.

(I currently run with a slightly modified GQview with IMAGE_TILE_SIZE
set to 2048 in order to allow smoother-looking image flipping.
However, this setting doesn't seem to affect the flip-skip-on-refresh
problem.)

I eventually just disabled the option, but it is convenient enough
that I'd like to start using it again.  Also, since the next stable
version is slated to come out soon, I thought it would be good to try
to take care of this for the release.  :)

Steve

-- 
Steven Mueller
[email protected]


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