Feature request: resize a window to a common size (width only)

[GoogleCodeExporter]

What steps will reproduce the problem?
1. apply diff http://pastie.textmate.org/1058799 to trunk revision 38 to see a 
possible solution

What is the expected output? What do you see instead?
As a web developer I like to have a shortcut to change a web browser window 
size to common screen resolutions (ex. 1024x768, etc.). 
It is ok if using the shortcut, positions the window on the left border of the 
screen and limits its width to 1024.

What version of the product are you using?
trunk revision 38

On what operating system(10.5 or 10.6)?
10.6

Are you using a dual monitor?
sometimes

Attach screenshots if it is a problem with the window position and size.
solution could look like: 
https://cms.jezek.ch/files/blog_images/shiftit_modified.png

Please provide any additional information below.
- I am not sure if the shortcut I have chosen is the best.
- adding more common resolutions would be cool: ex. 800, 1024, 1280, 1600, etc.
- a code review would be needed as objective c is not my primary language :-)
- hope you find time to merge my changes or use it as an inspiration, thanks

Original issue reported on code.google.com by patrick....@gmail.com on 25 Jul 2010 at 12:42