I have a pet bird who likes to play on the desk. Today she trampled on the keyboard while I was editing images and must have pressed some crucial keys. Now I find that when I press the ALT key while clicking on basic panel tone sliders, I no longer get a representation of clipped areas. The words 'reset tone' come up instead. I've looked on line but cannot find any reference to how to restore the response of the tone sliders so that I can see clipped bits. Any assistance is greatly appreciated.
Pressing the [Alt] key also changes 'Tone' into 'Reset Tone' for me, so that seems to be the default action. (LrCC2015.10 WIndows-10)
I do not know what might the bird have changed- Caps-Lock does not make a difference here.
For me, understanding the [Alt] action when moving the sliders takes a bit of interpreting channel clipping..
If you do not get the result as described in the Lr 'Help' file as quoted below, perhaps a reset of the Preferences file can help.
To view clipped image ares for each channel, press Alt (Windows) or Option (Mac OS) while moving a slider in the
Basic panel of the Develop module.
For the Recovery and Whites sliders, the image turns black, and clipped areas appear white. For the Blacks slider,
the image turns white and clipped areas appear black. Colored areas indicate clipping in one color channel (red,
green, blue) or two color channels (cyan, magenta, yellow)