Description of problem:
Anaconda can't writ the GRUB2 boot-record to a different partition. Only to the MBR of a disk.

Version-Release number of selected component (if applicable):
Anaconda 18.29.2 Fedora18 Beta

How reproducible:
Install on a system with many bootloaders on different partitions and disks. Use a system with BIOS. An UEFI-System acts different.

Steps to Reproduce:
1. Select custom disk layout.
2. If you are lucky, you will find the options for the bootloader behind the text "1 storage device selected" ;-)
3. There you an only select disks. 
  
Actual results:
The freshly installed Fedora 18 installed is not bootabel or existing MBR will be overwritten. 

Expected results:
Options to chose every exiting portion on the system.


Additional info:
I see the custom disk layout as some expert-tool in the installation process. But to hide options and information in the expert-tool is useless. But even for an experienced Fedora admin not guessable texts like "1 storage device selected" are really worse! Even Gnome does not hide Options in such a puzzling kind. The bootloader options should really be called "bootloader-settings" and not "1 storage device selected" or "selected disks".