There is a possibility to arrange layers to groups and handle together the layers belonging to the same group.
Click on the 
Layer settings button in the status line. Then you activate the Layer Properties Management dialog window. You can find on the right side of the dialog panel the layer groups buttons and settings possibilities.
Creating layer groups
Click on the Create group button, then a new group is instituted with a default name. If you click with right mouse button on the name and select the Rename menu, you can give a unique name to the group.
Add layers to a group
Select one or more layers, then hold down the left mouse button draw them above a layer group, and then release the mouse button. Behind the name of the layer group the number of layers that are in the same group appears between brackets.
Display Layer groups
Select a layer group from the list of All layers, then on the left side of the dialog window only the layers belonging to the selected group appear. You can qualify the appearing list if you switch on the Show used layers button.
The list of layers group contains two built in layer groups: if you select the All layers group, all the layers of the given window appear, if you select the Used layers group then that layers will be visible from the all layers, which contain elements unrelated to the position of Show used layers button.
Transactions with Layer groups
If you click with right mouse button on the name of a layer group, with help of the appearing shortcut menu you can modify the preferences of all layers at once: you can represent (On), or hide (Off), lock or unlock all layers in the given group at once.
Delete from group
Select a layer group from the list of Layer groups, then on the left side of the dialog window only the layers belonging to the same group appear..Select one or more layers then click on the Delete from group button.
The given layers are deleted only from the layer group, and they are available if you select the All layers group.
If you select layers from All layers and Used layers group, instead of Delete from group button you find the Delete button, which deletes the layers definitely.
Delete layers group
Select a layer group then click on the Delete button on the upper right corner of the dialog window. Then only the layer group will be deleted, the layers in it are available further if you select the All layers group.
2The layers groups have to be determined according to windows similarly to the layers.
Example:
In the following example it is a really great help using the layers group:
Start a new project.
Load in a DWG file, which contains more then 30 layers.
Create a new layer group: DWG layers.
Click on the right side on the Used layers group. Then on the left side only the layers imported from dwg drawing and the used layers can be found.
Move all layers from here to the DWG layers group.
Start design.
If the imported elements from dwg drawing are not needed, you can switch off or lock them in one step.