#722 Allow directory comparison to take account of DST

[Rob Allen]

NTFS modifies file timestamps to include an adjustment
for daylight saving time (DST), whereas FAT does not.
This means that files copied to a FAT volume from an
NTFS volume before DST comes into action cannot be
compared on timestamps alone after DST is in action.
This means that the files cannot be compared using the
"Modified Date" option.

More details can be found at:
http://www.codeproject.com/datetime/dstbugs.asp

It would be useful if WinMerge could take account of
this DST difference when comparing directories on NTFS
and FAT volumes, since it would allow use of the much
quicker "Modified Date" option.

I back up directories containing large binary files
from a NTFS drive to a FAT drive (such as a USB hard
disk), which I why I'd like to see this feature :) For
backing up data, comparing the modified date is usually
enough to work out if there's a difference. However,
having to compare the contents of the files can take
hours...

[Aaron]

This one has been around for a long time but it's still an issue to anyone who wants to compare folders stored on external media using the fast 'Modified Date' or 'Modified Date and Size' compare methods.

There is already a compare option to 'ignore time differences less than 3 seconds', so how about adding a new option as a quick one-line fix:

'Ignore time differences exactly one hour apart (FAT/DST)'

[gorokhmn]

Extremely important feature! It's really a pain to see twice a year back up files from NTFS drive to thumb drive with FAT to be EXACTLY one hour ahead/behind.

I vote for the previous comment:
There is already a compare option to 'ignore time differences less than 3 seconds', so how about adding a new option as a quick one-line fix:
'Ignore time differences exactly one hour apart (daylight savings)'

[Crashy]

It's 2022 and I confirm some would still benefit from that option.

:-)

By the way, my files differ by the one hour DST difference and the 3 seconds FAT difference. So both compare options would be useful to be selected individually.