Showing frame preview on Merge Summary does not work on Windows when clicking on File Selection column

[JohnstonJ]

Steps to reproduce:

1. On Windows 10, merge some DV files.
2. Click the blue hyperlink in the "File Selection" column in the Summary output of the merge.

Expected behavior: I'm assuming something should show up in the popup modal.

Actual behavior: blank/empty small-sized modal pops up.

Tested with nightly snapshot from dvrescue_GUI_22.12.20240731_Windows_x64.zip

Screenshot:

Debug log:

C:/Users/JohnstonJ/AppData/Local/Temp/mpout/Software/dvrescue_GUI_22.12.20240731_Windows_x64/cygwin/bin/bash.exe C:/Users/JohnstonJ/AppData/Local/Temp/mpout/Software/dvrescue_GUI_22.12.20240731_Windows_x64/tools/dvplay -M /cygdrive/c/Users/JohnstonJ/AppData/Local/Temp/mpout/Software/dvrescue_GUI_22.12.20240731_Windows_x64/scripts/mediainfo.sh -F /cygdrive/c/Users/JohnstonJ/AppData/Local/Temp/mpout/Software/dvrescue_GUI_22.12.20240731_Windows_x64/scripts/ffmpeg.sh -O - -S |9840000|9240000|9960000| -s C:/VideoProject/Johnston3/trunc/Johnston3-pass1.dv|C:/VideoProject/Johnston3/trunc/Johnston3-pass2.dv|C:/VideoProject/Johnston3/trunc/Johnston3-pass3.dv|C:/VideoProject/Johnston3/trunc/Johnston3-pass4.dv|C:/VideoProject/Johnston3/trunc/Johnston3-pass5.dv -b 9960000 C:/VideoProject/Johnston3/trunc/Johnston3-pass1.dv_merged.dv

success

[libbyhopfauf]

same issue reported here: https://github.com/mipops/dvrescue/issues/952#issue-2656625820

@BrendanReidy