Index: sites/trunk/wordpress.org/public_html/wp-content/themes/pub/wporg-developer/searchform.php
===================================================================
--- sites/trunk/wordpress.org/public_html/wp-content/themes/pub/wporg-developer/searchform.php	(revision 2294)
+++ sites/trunk/wordpress.org/public_html/wp-content/themes/pub/wporg-developer/searchform.php	(working copy)
@@ -51,11 +51,23 @@
 					'wp-parser-class'    => __( 'Classes',   'wporg' ),
 					'wp-parser-method'   => __( 'Methods',   'wporg' ),
 				);
+
+				$qv_post_type = array_filter( (array) get_query_var( 'post_type' ) );
+
+				if ( in_array( 'any', $qv_post_type ) ) {
+					$qv_post_type = array_keys( $search_post_types );
+				}
+
 				foreach ( $search_post_types as $post_type => $label ) {
-					$qv_post_type = (array) get_query_var( 'post_type' );
+					$checked = checked( in_array( $post_type, $qv_post_type ), true, false );
+
+					// Set functions as default if no post types are found in the query.
+					if( empty( $qv_post_type ) && ('wp-parser-function' === $post_type ) ){
+						$checked = ' checked="checked"';
+					}
 				?>
 					<label><input type="checkbox" name="post_type[]" value="<?php echo esc_attr( $post_type ); ?>"
-					<?php checked( ! is_search() || in_array( 'any', $qv_post_type ) || in_array( $post_type, $qv_post_type ) ); ?> /> <?php echo $label; ?></label>
+					<?php echo $checked; ?> /> <?php echo $label; ?></label>
 				<?php } ?>
 		</div>
 	</form>