Otter browser frontend and dynamic area issues

I’ve been using the Otter browser RISC OS frontend and in general it has been a useful addition to Otter functionality. However, whereas Otter by itself would consistently give up claimed dynamic areas on quitting and relaunching, under the RISC OS frontend this does not happen IME, with the result that the dynamic area enlarges to the point – in my case to around 400000K on this Pi3 – where the browser becomes unresponsive. The only solution is to shut down and restart the Pi. I’m running a recent high-vector ROM build (but the behaviour described above doesn’t alter under a low-vector ROM). Otter’s !Run file contains the following:

X removeda otter-browser
X rmreinit somanager
X removeda “Qt mmap”
X removeda “Webkit Fast Malloc”
X removeda “Webkit GC Heap”
X removeda “Webkit VM Stack”