Main window design proposal

[Hongli Lai <hongli telekabel nl>]

I think the current main window design is not good enough.
Currently it looks like this:

+----------------------------+
|       | Thread             |
| Mail  | list               |
| boxes |                    |
|       +--------------------+
|       |                    |
|       | Message body       |
|       |                    |
|       |                    |
+-------+--------------------+

This has a disadvantage: there's less space for the
message body viewer widget.
Yes, I know the mailbox list can be hidden, but a lot of people
switch mailboxes very often.

So I'm proposing a new design that looks like this:
+----------------------------+
|       |                    |
| Mail  |   Thread list      |
| boxes |                    |
|-------+--------------------+
|                            |
|        Message body        |
|                            |
|                            |
+----------------------------+

Saves a lot of space, doesn't it?
Please consider this.
Or at least make it configureable.

Thanks.