The unprecedented effective area of the Athena mirror system will provide very high photon rates for bright x-ray sources (e.g., for the Crab pulsar). This necessitates very high frame rates and flexible readout modes which can be achieved by operating the central DEFET matrix in a window mode of e.g., 16 rows. Due to the excellent point spread function of 5 arc sec on-axis, a pixel size of () was chosen for the central matrix. The matrix will be subdivided into two halves, each read out in parallel by four VERITAS-2 ASICs. With this concept, the WFI count rate capability will be optimized if the focal spot is located and maintained in a relatively precise position on this DEPFET sensor, which spreads the photons between the two readout halves. The feasibility of such a scheme and the impact on the pointing accuracy and stability shall be explored in the study phase. With the option to double the number of readout channels, two rows per half can be read out simultaneously. This allows the full chip to be read out in or a 16-row window (corresponding to five times the on-axis PSF) in . Since this option significantly increases the complexity of the detector and its power dissipation, therefore, a detailed trade-off is necessary during the technology development phase.