[openbox] disable resizing from top of window?

[Joey Morris]

I'd like to disable the ability to resize a window using the mouse when grabbing
the top edge of a window. I find that I keep accidentally resizing a window when
I'm just trying to grab its titlebar to move it. Is there a way to do this using
theme settings? I've looked through the theme documentation but haven't seen
anything that would do it. It appears that the resize area is controlled by the
padding.height setting, but even when that's 0 I get the resize cursor at the
top of the window (plus I don't like how compact it is with padding set to 0).