8.8 Nesting Layers

Nesting doesn't necessarily mean that one layer appears inside another layer; rather, it means that the HTML for one layer is written inside the code for another layer. The nested layer itself can appear anywhere on the page (see Figure 8-10). The main benefit of nested layers is that the parent layer—the layer containing the HTML of one or more other layers—can control the behavior of its child layers.

For example, suppose you create one layer and nest two layers inside it. If you move the parent layer on the screen, the two child layers follow it, which gives you an easy way to move several layers in unison. Furthermore, the parent layer can control the visibility of its children. When you hide the parent layer (see Section 12.4.5), the nested layers also disappear.

An inner nested layer doesn't necessarily appear inside the outer layer. The HTML for the layer at far right, for example, is nested inside the large gray box layer. Yet a layer that appears on top of another layer isn't necessarily a nested layer, either; the light gray box here isn't nested at all. But the HTML for a nested layer does appear within the code for the outer layer. To identify a nested layer, click a Layer marker (the shield) within a layer; the nested layer's selection handle appears.

Here's how to create a nested layer:

• While pressing the Ctrl () key, drag one layer in the Layers panel (see Figure 8-8) onto another layer. The dragged layer becomes the child of the layer you drop it on, and its name appears indented in the Layers panel, also shown in Figure 8-8.

  To un-nest a layer, drag it above or below the parent layer in the Layers panel. (Doing this places the code for the nested layer directly after the opening <div> tag of the parent layer.)

• Use the Insert Div Tag button on the Layout tab of the Insert bar, or choose Insert Layout ObjectsDiv Tag. In either case, the Insert Div tag window appears (Figure 8-11). Select the name of the layer you wish to nest inside another layer; choose either "After start tag" or "Before start tag" from the first Insert menu; then choose the name of the parent layer from the second menu.

• Click inside a layer, and then choose InsertLayer. You get a new, nested layer inside it. This technique and the next one, however, creates a new layer using Dreamweaver's inline layer style—the same type of style as when drawing a layer. This isn't the best option as described in Section 8.5.

• Drag the Layer tool from the Insert bar and drop it inside a layer on the page. (Note that this isn't the same procedure described in Section 8.5, in which you click the Layer button and then drag in the document window.)

The Insert Div Tag tool makes creating a nested layer easy. Just make sure to select either "After start" or "Before end" of tag option (top), followed by the name of the parent layer (bottom).

The Layer marker for a nested layer appears inside the border of the outer layer.

8.8.1 Undoing nested layers

If you later want to un-nest a nested layer, just drag its Layer marker to a new spot in the document window—outside of any other layers.