you want to mark all pieces 1st and copy or cut them to clipboard afterwards in one step. I afraid this is hard to do by keyboard only. [...] The current selection is always cleared on cursor move. That means e.g. after a 'Shift-cursor down' selection you'd need the mouse to add more selections...
Well, I didn't say it had to be available by keyboard only.
OTOH, just like Ctrl-Click means "add what I just clicked on to the multi-selection without changing what had been previously selected", you could have Ctrl-(arrow) mean "move cursor without altering any selections", so you would make one selection by holding down Shift and using the arrows, then hold down Ctrl to move to the beginning of the next selection, then hold down Shift
and Ctrl to add the new text to the multi-selection and so on. It's feasible and quite intuitive, given the long history of Shift-Click and Ctrl-Click selections.
Sure, you need more key presses to build up your final clipboard contents, but on the other hand it supports to copy or cut each selected snippet separately.
That's not an advantage, it's just what's available now. It wouldn't go away if what I said were added. Sometimes you want separate pieces copy-pasted separately and sometimes you want them together. It's different tools for different jobs.
