This tab is accessed from the Layout Manager in Theme Builder 3.0 and above.The Layout tab allows you to customise which panels are shown within the selected layout...
The toolbar at the top of the layout tab allows you to select which panels are shown in the layout.
Click any of the buttons on the toolbar and the corresponding layout panel will be toggled on or off (depending on it's current state).
Note: The sliders can only be enabled if their corresponding sidebar has been enabled.
When you click on a panel in the Layout Preview area, the Panel Editor is shown at the bottom of the page allowing you to customise the panel (background, borders, etc) and it's contents.
Note: Panel contents are not shown in the Layout Preview.
Read Layout Hierarchy to find out