so far i've come up with a kind of a hack solution, but it works ok. I am using the middle mouse drag and drop functionality along with the absolute positioning available through formLayout to allow the user to drag and drop the zoomed area wherever they want. i'm just using a grayed-out button as the drag and drop element. the button's size scales to reflect the size of your viewer with respect to the overall area of the image plane. unfortunately, the screen does not update until you drop. i wish there were some way to get real-time info on the cursor position.
i've found another fucntion called draggerContext. this WILL give you realtime feedback of cursor position, but only in a GL modeling pane. i'm going to try to use this to create an overscan zoom and pan that works akin to maya's regular zoom/dolly and pan/track, with a simple mouse drag activated by a depressed key.
i was also thinking that what you described would work very well, using an actual openGL modeling panel. It would only be really efficient though, if it were a stand-alone floating model panel, like the hardware render buffer. there are some controls for scaling the the hardware renderer and docking it to panels, but i still haven't found a way to get rid of the menus, time slider, and other extraneous elements. what i really need to know is if there is a way to create custom floating modeling panels.
anyone out there with some clues to how to do this?
-chad