DSP to WM to SAP and back

I would like to write a robust DSP application such as WmTNWeb or the WM Admin page. The application will invoke a WM flow to access R3 in SAP through a remote function call. I have found developing DSP on just an editor to be painful. Does an IDE exist for developing DS pages? Does anyone know of a tips / FAQ website or page for DSP development? I am currently on 4.0 on a Sun.