There are many threads on bbpress forum where people are almost frustrated with the problem of making their theme work with the new bbpress plugin version.
Particularly, they have this problem with making a theme, child-theme and applying it to the forum.
Ex: Your blog has sidebar and you don’t want to have sidebar in your forum.
I had the same problem, and solved it after trying it for a long time. Now I feel like, why the hell did I spend so much time on this simple thing
Without much delay: In this example I’ll illustrate by keeping the official “bbPress (Twenty Ten)” theme in mind, which is present in /wp-content/plugins/bbpress/bbp-themes/bbp-twentyten folder by default when you install the bbpress plugin.
1. Move twentyten theme from /wp-content/plugins/bbpress/bbp-themes/ to /wp-content/themes/.
Note: You can rename the folder with any name you like.
2. Now get into twentyten theme and edit style.css file. Add Template: yourWordpressThemeFolderName (yes add the folder name of your present wordpress theme) to your style.css files comment section, as shown below.
If your WordPress theme name is MyTheme. You have to add Template: MyTheme to style.css file of twentyten bbpress theme.
* Theme Name: bbPress (Twenty Ten)
* Theme URI: http://bbpress.org
* Description: Adds bbPress forums to the Twenty Ten theme
* Author: WordPress and bbPress teams
* Version: 1.2
* Tags: bbpress, black, blue, white, two-columns, fixed-width, custom-header, custom-background, threaded-comments, sticky-post, translation-ready, microformats, rtl-language-support, editor-style
* Template: MyTheme
* This file intentionally left blank. Styles are enqueued in functions.php
* 1 – ./css/bbpress.css
3. Now you have made the twentyten theme a child theme of your present WordPress theme.
4. Now log into your WordPress dashboard. Goto Appearance, and activate the child-theme.
To remove the sidebar:
Goto the child theme, inside that bbpress folder and comment these line of code /* < ?php get_sidebar(); ?> */ in page-front-forums.php and page-front-topics.php files.
If this method does not work, then create a file called sidebar.php and drop it inside your main theme folder. sidebar.php must be blank.
Now Reload your forum :p