Hmm, thanks for pointing this out. But I'm slightly baffled, for the commands you gave (flush-lines, M-%, M-S-%) that's fine - transient mode with keyboard (bet

Hmm, thanks for pointing this out. But I'm slightly baffled, for the commands you gave (flush-lines, M-%, M-S-%) that's fine - transient mode with keyboard (between point and mark) and with a mouse, they are the same thing. Transmode is just highlighting AFAICS (between point and mark) and that mode quits the moment you release the mouse (leaving mark where you started the drag, point where you ended it). The convention of "operate only on stuff between point and mark" is necessary, mouse or no, and has been there since forever. But I'm no expert!