fix checkSelected

src/main/java/de/com/baseband/clientboot/CBWindow.java

@@ -57,13 +57,13 @@ public class CBWindow extends JFrame implements WindowListener {
         int max = 0;
         while (list.get(selected).callback == null) {
             if(wasMovingUp) {
-                if(selected-- == 0) {
+                if(--selected < 0) {
                     selected++;
                     wasMovingUp = false;
                 }
             }
             else {
-                if(selected++ == list.size()) {
+                if(--selected == list.size()) {
                     selected--;
                     wasMovingUp = true;
                 }