GIMP Plugin Registry

Toggles the visibility of selected layers. Purpose is to see directly the influence that one layer or a group of layers has to the whole image in comparison to the influence of another layer or group of layers.
The visibility-status of the selected layers (by anchor) is switched from visible to invisible and vice versa
each time the script is executed.
So the best way is to use the script with a shortcut-key.
The script installs itself under layer -> stack -> Toggle Visibility

how it works