For this period, I have been working on getting resizing to work from within Haiku, rather than just in bfs_shell. In its current state, the code works, sometimes, if you don't stress it too much and write data to the partition while resizing. On the bright side, recovery from various errors is working well :). In terms of functionality, the only thing missing is the ability to grow full or almost full file system. The problem with this is that we need to grow the bitmap that tracks allocated blocks before we can actually make use of the new blocks. This can be overcome with a little slyness, but it's a bit of work, and adds some complexity.
This is a companion discussion topic for the original entry at https://www.haiku-os.org/blog/ahenriksson/2012-08-06_bfs_partition_resizer_threequarterterm_report/