registered sidebars with capital letter in the ID don't get loaded

[wjm]

if you use register_sidebar() and set ID to have a capital letter, it will be displayed in the widgets section but its widgets won't get loaded.

register_sidebar(array(
'name' => 'RightSideBar',
'id' => 'Rsidebar',
));

it won't work but

while...

register_sidebar(array(
'name' => 'RightSideBar',
'id' => 'rsidebar',
));

... will work.

This has to do with dynamic_sidebar() using sanitize_title() to sanitize the id,
the thing is that sanitize_title() (which calls sanitize_title_with_dashes()) will turn every upper case to a lower case, and later it will look in $wp_registered_sidebars for the key which is non-existant.

This patch sanitizes the sidebar ID at the time of registering it,
so using
'id' => 'Rsidebar',
or
'id' => 'rsidebar',

registers the same sidebar.

[wjm]

this issue was found here,
​http://www.wpquestions.com/question/show/id/713

[nacin]

Duplicate of #11160.