APT already has a signal handler for SIGWINCH, in order to resize the progress bar. The problem is that after APT finds out about the resize it clears the last

APT already has a signal handler for SIGWINCH, in order to resize the progress bar. The problem is that after APT finds out about the resize it clears the last line on the screen, but it's a visual line, which is only a part of a semantic line which was wrapped after shrinking the terminal window. APT doesn't know how many visual lines the progress bar takes after being rewrapped by a resize, so it doesn't know how many lines to clear. It could try to compensate by remembering the old width in characters, looking at the new one and calculating what rewrapping would result in, but that would probably not be very reliable across different terminals. Redrawing everything is annoying from UX point of view, because it breaks copying lines out of the terminal. Instead of getting a bunch of lines separated by line feeds corresponding to semantic lines, the user gets a bunch of lines corresponding to the visual lines in the terminal (so a lot of lines broken, some of them midword), including loads of meaningless whitespace. I wish the modern terminal was less of an old terminal emulator and more of a GUI for displaying pipelines. So no ncurses-like applications, such as vim, more first-class support for progress bars (instead of the hacks that we have), support for jumping between the lines in scrollback where the user typed in the commands, no possibility of breaking the terminal state (such as what happens when I hit Ctrl+C in the password prompt of openvpn) forcing the user to run "reset", etc. etc.