move con_focus to con.c

src/con.c

@@ -74,6 +74,24 @@ void con_detach(Con *con) {
     }
 }
 
+/*
+ * Sets input focus to the given container. Will be updated in X11 in the next
+ * run of x_push_changes().
+ *
+ */
+void con_focus(Con *con) {
+    assert(con != NULL);
+
+    /* 1: set focused-pointer to the new con */
+    /* 2: exchange the position of the container in focus stack of the parent all the way up */
+    TAILQ_REMOVE(&(con->parent->focus_head), con, focused);
+    TAILQ_INSERT_HEAD(&(con->parent->focus_head), con, focused);
+    if (con->parent->parent != NULL)
+        con_focus(con->parent);
+
+    focused = con;
+}
+
 /*
  * Returns true when this node is a leaf node (has no children)
  *