Jump to region start/end

Now with ardour 5.12(Linux) i miss the possibility to jump to region starts and ends back and forward. It worked with ardour 4,7 with the cursor keys. The manual does not mention anything about this.
additional but OT. is that the function “region freeze” is not explained anywhere.(Or I have not found it)

Meanwhile II found it. It’s “playhead to next/previous region boundary” with “Shift-Alt-Right”/“Shift-Alt-Left”. it’s sad that it can not be changed in the Alt-K window