Double clicking on a thumbnail should display the image in the embedded viewer / floating viewer / viewer on second monitor, depending on the configuration.
I recently created a couple of panoramas (TIFs) using Hugin and, when double clicked, they open outside PSU in a 3rd party image viewer instead - which obviously shouldn't happen. TIFs generated by other software seem not to be affected.
When I get chance, I'll try exporting to other image formats from Hugin and report back, but it may be a few days.
Currently on V6 build 3546 on Win 8.1, but was also happening in v5 before I upgraded, so not new.
Images exported from Hugin open in 3rd party viewer
Re: Images exported from Hugin open in 3rd party viewer
Your files are probably larger than the configured Processing limit. Set that to a higher value.
Re: Images exported from Hugin open in 3rd party viewer
Thanks Hert
Yes, that was the cause - I hadn't spotted that setting before!
I've now set the limit at 999 MB (as the field is only big enough to display 3¾ digits).

Yes, that was the cause - I hadn't spotted that setting before!
I've now set the limit at 999 MB (as the field is only big enough to display 3¾ digits).