Refresh doesn't work when comparing archive files

[jmairboeck]

When comparing archive files (e.g. zip files), Refresh (F5) doesn't work. The display is refreshed, but the actual contents don't change.

Steps to reproduce:

• open two archive files to compare
• change one of the archives outside of WinMerge so that one or more files inside the archive are changed and cause a difference to before
• Refresh WinMerge

Expected result: the two archive files are read again and the differences are updated accordingly.

Actual result: the comparison is still the same as before, even though the display has been refreshed.

I suspect this is because for the comparison, the two archives are extracted to a temporary folder each and then normal folder comparison is used on them. These temporary folders should be updated when refreshing in WinMerge.