Fix resize handling on click on borders (did not correctly use orientation)

src/con.c

@@ -515,6 +515,43 @@ Con *con_next_focused(Con *con) {
     return next;
 }
 
+/*
+ * Get the next/previous container in the specified orientation. This may
+ * travel up until it finds a container with suitable orientation.
+ *
+ */
+Con *con_get_next(Con *con, char way, orientation_t orientation) {
+    DLOG("con_get_next(way=%c, orientation=%d)\n", way, orientation);
+    /* 1: get the first parent with the same orientation */
+    Con *cur = con;
+    while (con_orientation(cur->parent) != orientation) {
+        LOG("need to go one level further up\n");
+        if (cur->parent->type == CT_WORKSPACE) {
+            LOG("that's a workspace, we can't go further up\n");
+            return NULL;
+        }
+        cur = cur->parent;
+    }
+
+    /* 2: chose next (or previous) */
+    Con *next;
+    if (way == 'n') {
+        next = TAILQ_NEXT(cur, nodes);
+        /* if we are at the end of the list, we need to wrap */
+        if (next == TAILQ_END(&(parent->nodes_head)))
+            return NULL;
+    } else {
+        next = TAILQ_PREV(cur, nodes_head, nodes);
+        /* if we are at the end of the list, we need to wrap */
+        if (next == TAILQ_END(&(cur->nodes_head)))
+            return NULL;
+    }
+    DLOG("next = %p\n", next);
+
+    return next;
+}
+
+
 /*
  * Returns a "relative" Rect which contains the amount of pixels that need to
  * be added to the original Rect to get the final position (obviously the