I wanted to share the following.
Since I had now and then tone/color differences between an exported file versus the middle screen image in the darkroom, I welcome very much the new toggle switch for the darkroom, forcing the pixel-pipe processing to use the whole image data. It works as expected in dt 4.7 (thanks Hanno!). However this puts a very high load on the gpu. Now if occasionally the 2nd preview window is also active (something I use rather often) and this toggle switch is also “on”, I saw my opencl processing going into time-out and thus the pixelpipe processing being executed in the CPU. That takes extremely long. Hence I started tuning the opencl_mandatory_timeout parameter in the darktablerc file. With opencl_mandatory_timeout=5000 the timeout status was still reached. I ended up with opencl_mandatory_timeout=9999.
Of course I will, as much as possible, avoid to leave the 2nd preview window active when invoking this new toggle switch.