[Plugin: Widgets in Columns] Fails for widget IDs greater than 9

This is a very useful plugin. Other people as well as myself are happy to have found it.

Nevertheless, there is a malicious bug. Using more than 9 widgets of one widget class will result in errors. The error occurs in your function dynamic_sidebar_params(). The current code is
$widget_id = substr( strstr( $params[0]['widget_id'], '-' ), -1 );
It only uses the last character of string $params[0]['widget_id'], which fails if the widget id is ‘text-10’, for example.

An alternative code line may be
$widget_id = substr( $params[0]['widget_id'], strrpos( $params[0]['widget_id'], '-' ) + 1 );
This gets always the whole part of the string after the last ‘-‘.

http://wordpress.org/extend/plugins/widgets-in-columns/