When I import a set I put it on the bottom layer.
But it is still active and moves around if I make a wrong click.
Command/Z puts it back but I would simply like to disable that layer
from being chosen all of the time. Is that possible?
Disable a layer
You can only select the current layer unless you have specifically enabled another layer to make its objects selectable when it is not current. Selectability is controlled by a checkbox in the layers table next to the visibility checkbox. If you create a new layer above your imported graphic and make it the current layer, you won't accidentally select and move the graphic. In LXFree for Java, making a new layer is done with the popup button under the layers table in the Inspector's document tab.