Shortcut for entire layer to be Transparent Lens ?

[dungbtl]

Is there a way to select all within a single Layer
to go transparent? maybe at a fixed %, i.e. 50%

Or maybe input a % dialog?

I've come across a few times where I had to manually
do a Trans Lens on objects with other layers open.
In object manager there's too many objects to select
and if the list is long it takes forever to catch up selecting.

Thanks all

This would be for Corel X4