I'd like to create actions, so I need to know some hot keys for the Layers' panel.
For example, I know that alt+[ and alt+] switch between layers.
ctrl+, hides a current layer and shows it again if it's active.
BUT as soon as I move to another layer from a hidden one, I can't come back with alt+[ or alt+] !!!
It just skips a hidden layer and selects a neighboring one which is visible.
How can I move to a hidden layer again with the hot keys???
The Relative keys select visible layers only as you found out.. Alt+, Bottom visible Alt+. Top visible Alt+[ next lower visible Alt+] next upper visible layer. With Actions the only way to select a layer with its visibility off is by selecting the layer by Name. You may be able to create a couple of scripts the do what you want and assign shortcuts to execute them from Photoshop UI. But in an action you would need to record a script step to use these in an action if the shortcut do not record a script step in your action. Script can get all the layers in an array find the current active layer position in the array and activate the next layer in either direction. There is a Photoshop Scripting forum if you need help.
seems to be too difficult... I've found another way - not to make a layer invisible, but to change the opacity to 0%