Index: com/simsilica/lemur/core/GuiControl.java                                                                                                                                                                                              
===================================================================                                                                                                                                                                          
--- com/simsilica/lemur/core/GuiControl.java    (Revision 1005)                                                                                                                                                                              
+++ com/simsilica/lemur/core/GuiControl.java    (Arbeitskopie)                                                                                                                                                                               
@@ -49,7 +49,7 @@                                                                                                                                                                                                                            
                         implements FocusTarget                                                                                                                                                                                              
 {                                                                                                                                                                                                                                           
     private SafeArrayList<GuiComponent> components = new SafeArrayList<GuiComponent>(GuiComponent.class);                                                                                                                                   
-    private GuiComponent layout;
+    private GuiLayout layout;
     private volatile boolean invalid = false;
     private Map<String,GuiComponent> index = new HashMap<String,GuiComponent>();
     private Vector3f preferredSizeOverride = null;
Index: com/simsilica/lemur/component/TbtQuadBackgroundComponent.java
===================================================================
--- com/simsilica/lemur/component/TbtQuadBackgroundComponent.java       (Revision 1005)
+++ com/simsilica/lemur/component/TbtQuadBackgroundComponent.java       (Arbeitskopie)
@@ -47,8 +47,59 @@
 
 
 /**
- *
- *  @author    Paul Speed
+ * A texture-covered background area for drawing background areas.<br>
+ * The texture will be stretched using a three-by-three raster to cover the
+ * required size.
+ * <p>
+ * The defining properties are:
+ * <ul>
+ * <li>the texture itself;
+ * <li>what parts of the texture are to be mapped to what parts of the raster
+ * this is done by defining the center rectangle of the raster, in terms of
+ * texture coordinates;
+ * <li>an image scale; it does not apply to the center rectangle but everywhere
+ * else;
+ * <li>a Z coordinate to define stacking order;
+ * <li>whether to use lighting (via Lighting.j3md) or not (via Unshaded.j3md).
+ * </ul>
+ * 
+ * The raster rectangle is defined via the x/y coordinates of the bottom left
+ * and top right corner of the center rectangle that takes up all stretching,
+ * like this (the directions in which each texture area may stretch is indicated
+ * via arrows):
+ * 
+ * <pre>
+ *    +---+--------------+-------+
+ *    |   |    <----->   |       |
+ * y2 +---+--------------+-------+
+ *    |   |              |       |
+ *    | ^ |       ^      |   ^   |
+ *    | | |       |      |   |   |
+ *    | | |    <----->   |   |   |
+ *    | | |       |      |   |   |
+ *    | v |       v      |   v   |
+ *    |   |              |       |
+ * y1 +---+--------------+-------+
+ *    |   |    <----->   |       |
+ *    +---+--------------+-------+
+ *       x1             x2
+ * </pre>
+ * 
+ * All x and y coordinates relative to the bottom left corner of the texture.
+ * <p>
+ * <b>Common pitfalls</b>
+ * <ul>
+ * Placing controls on a fractional coordinate. Something to watch out for when
+ * centering controls.
+ * <ul>
+ * Having a contrast at the border between stretched and unstretched texture
+ * zone (e.g. a black border and a white center). Stretching involves
+ * interpolating colors with the neighbouring pixels (i.e. you'll get a
+ * black-to-white color gradient). <br>
+ * The easiest workaround is to make the border one pixel wider so that the
+ * contrast will be safely inside the unstretched area.
+ * 
+ * @author Paul Speed
  */
 public class TbtQuadBackgroundComponent extends AbstractGuiComponent 
                                         implements Cloneable, ColoredComponent