I just realized that the GrowWindow* commands make a window think it is maximized - so you can't resize it, and you can only move it along the other axis (i.e. after GrowWindowDown, you can only slide it sideways, no moving up or down). It leaves this state when you Unmaximize it.
I am not sure if this is a bug or feature, but it was definitely unexpected, especially as similar commands in Openbox which I am now checking out leave the window in normal movable and sizable state. -- Ham is for reading, not for eating.
