I'm just starting this thread to raise awareness that something is "funky" about image caching on ModularGrid.
Mostly this affects rack preview images. When a rack is updated, on first load (when generation of a new preview image gets triggered), the correct image is loaded. On subsequent loads, a stale image usually gets loaded from the browser cache until that old image eventually ages out (or the cache is manually cleared). This behavior is mostly harmless.
I ran into trouble when trying to upload an improved image for a module just now, though. After uploading the new image, it appeared as though nothing had happened, so I tried again. Again, nothing seemed to happen, except the second time around I noticed the previous image I had uploaded was now listed in the "Panel Versions" sidebar. Realizing this was probably the same caching problem, I loaded the module page in another browser, and the main panel image showed the updated image as expected.
This isn't great, since it means I uploaded a duplicate module image. (It looks like this happens somewhat frequently, since I see duplicate module images more often than I'd expect if this were purely accidental.)
The problem seems to be that ModularGrid always uses the same URL for these images, even after they're updated, and allows them to be cached. Strangely, this also seems to affect preview generation somehow, since rack previews which include the module I mentioned above are continuing to use the old HEAD image for the moment, even as they're regenerated. (I confirmed the rack does actually use the new panel image in another browser, but the preview still does not.)
None of this is that big a deal, but it would be great if this were fixed at some point (and perhaps some method was added to remove duplicate panel images).
