[USER=126614]@polarwoc[/USER]
Yeah, this 'feature' is extremely useful for isolating a layer mask too.
I often end up with an outline on a mask and just need to 'fill in' the rest of it....toggling the mask by Alt + LMB displays just the greyscale mask ready to paint on.
[USER=109010]@Rich54[/USER]
'Nothing happens' is par for the course with PS isn't it? Haha
If it makes you feel better I use CC 2019, IMO still the most stable version, and it too does absolutely nothing with ALT + LMB on the thumbnail, just the mask.
Lots of things changed after CS5, layers had a big change in the way they work, especially with vector masking, totally different to CS5. Personally I thought it was better back in CS5, easier to get what you wanted but hey, you can't stand in the path of progress right? Yeah, right.
Oh and BTW... ALT + Eye icon is THE MOST ANNOYING THING EVER!
Regards.
MrToM.