Another set of changes have been pushed to https://bitbucket.org/jas/drawterm-cocoa that support resize/reshape of the OS X window. There are still a few drawing glitches once a window is resized, but those should be fixed in short order.
The drawterm-cocoa fork has a branch named 'p9' that I've used for these changes. Use that branch until everything is merged back to default. All comments & criticisms are welcome through any communication vector available. This work has been sponsored and © coraid 2012 under the plan 9 open source license. -jas