I understand that stacking is an important feature for people (including myself) who shoot raw+jpg. I can see however that it has been a recurring issue in the forums -and probably for support as well.
Like many users, I find FPV very useful for culling early in the workflow, then later as I edit some photos and save them edited (usually as .psd, sometimes as .tif) into a subfolder, if I do not change the filename before saving then stacking becomes an impediment. I cannot easily compare the edited photos with the original, which I would like to do before publishing or further editing.
I can see two solutions:
1- I (and other users in the same situation) adjust to this constraint imposed by stacking and get into the habit of renaming the edited files.
* OR
2- FastPictureViewer provides an option to disable stacking based on the file modified date and time. With this option selected, files with the same filename would not be stacked if their modification date differs by more than a few minutes (which indicates that they are likely to have been edited). This option would be off by default so as not to change at all the behaviour of FPV for current users when they upgrade, unless they consciously want to change that behaviour.
This would then improve FPV when used for the purpose of editing without damaging its functionality for early culling.