Prevent moving out of fullscreen containers.

src/move.c

@@ -169,6 +169,12 @@ void tree_move(int direction) {
     while (above->parent != same_orientation)
         above = above->parent;
 
+    /* Enforce the fullscreen focus restrictions. */
+    if (!con_fullscreen_permits_focusing(above->parent)) {
+        LOG("Cannot move out of fullscreen container\n");
+        return;
+    }
+
     DLOG("above = %p\n", above);
     Con *next;
     position_t position;