In the layer stack at the bottom right corner of BlueBrick, only one Layer can be selected at a time. The selected layer is displayed with a gray background 10. To select another layer, simply click on it in the layer stack. The notion of selected layer is important because it is the active layer in which all your layout modifications will take place. Conveniently, when you move your mouse over the layout panel, the mouse cursor will change according to the type of the currently selected layer.
The Layer Toolbar at the bottom of the layer pane provides the basic layer controls:
The layer stack is rendered as you may expect: the layers on top of the stack are covering the layers of the bottom. This allow you to place the LEGO® parts above the tables for example, as shown on the screenshot. But you can of course reorder the layer stack: moving layers to the front or back is done with buttons 1 and 2 respectively. It will move the contents of the layer tab 10, which you have selected.
Adding layers is done with buttons 3 through 7. Their functions will be discussed in the five different type of layers section. Note that each new layer you add, will be placed at the front. If you wish to have it below a previous layer you must use the "move layer down" button 1.
Removing layers can be done by selecting the layer tab and pressing button 8.
Layer properties can be changed by double clicking on the layers 10 or through the Edit > Current Layer Options... menu. This includes changing the layer name and its transparency. Other properties differ depending on the layer type.
Layer visibility can be changed by clicking on the eye icon 9 of the layer you want to hide, or unhide. The visibility can also be changed in the layer properties.
For some layer you can show or hide of the part's hulls by clicking on the rectangle icon 18. The hull visibility can also be changed in the layer properties.