Select all objects on a specific layer

Make it current, and then on the Edit menu, point to Select, and then click All.

Prevent selecting objects on all layer but the current one

On the Layers palette, click the Freeze icon in the toolbar. The icon before the layer name in the Layers palette, changes to . Now, even if you click an object on other layers, it is not selected.

To enable again selecting of objects on other layers

On the Layers palette, click the Freeze icon again.

Note

By default, you can select any object on any layer. The selection cannot contain objects on different layers.

On the Layers palette, a icon marks the layer that contains selected objects.

You can select objects on locked layers, although you cannot edit them.

By selecting an object on a layer, you target (switch to) that layer - you make it the current layer. All object you add after that, are added to that layer.