diff -u b/core/includes/common.inc b/core/includes/common.inc
--- b/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -3728,7 +3728,13 @@
  *   - If this element has an array of #theme_wrappers defined and
  *     #render_children is not set, #children is then re-rendered by passing the
  *     element in its current state to theme() successively for each item in
- *     #theme_wrappers.
+ *     #theme_wrappers. Since #theme and #theme_wrappers hooks often define
+ *     variables with the same names and this can cause conflicts, it is
+ *     possible to explicitly specify which theme wrapper hook each attribute is
+ *     passed to by renaming it to #wrapper_wrappername_attributename. For
+ *     example, to ensure an attribute that would normally be named #attributes
+ *     is only used by the 'container' theme wrapper, it can be renamed to
+ *     #wrapper_container_attributes.
  *   - If this element has an array of #post_render functions defined, they are
  *     called sequentially to modify the rendered #children. Unlike #pre_render
  *     functions, #post_render functions are passed both the rendered #children