You could easily script something very, very similar to what you have in mind. All you have to do is on me:*:PART:#:, savebuf the current buffer, open a window -kE $+(@,$chan), set the titlebar correctly as it is shown in the channel, loadbuf the buffer back (add the nicks, if you like), and then allow the rest of the part to complete, closing the window. If you rejoin the same channel on the same connection, you can reverse the process if you so chose (though this would likely impact logging unless you did the slooooooow loop through the buffer, if it's large, and used the echo -g parameter to prevent the lines from getting logged again).