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I tried the first experiment in chapter 5 in the Metafontbook: ran mf, typed \relax and drawdot (35,70); showit;. This opened a window entitled Metafont, but containing nothing. What's missing? Using TeXlive 2020 on Linux.

PS. After adding drawdot (65,70); showit; I see both dots.

PS II. Which have now disappeared, after I changed window-manager workspace and back.

PS III. Typing showit; before the first drawdot opens a window and allows the first dot to be seen, but after having switched workspaces and back, I haven't found any way of bringing the picture back, short of drawing something more and showing it.

Toothrot
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  • I don't know but I can confirm I get the same behaviour, on a different distribution (TeX Live 2017 on macOS). – ShreevatsaR Sep 02 '17 at 14:20
  • I got a dot when I tried using mf from tl2017, see image. – David Carlisle Sep 02 '17 at 15:16
  • @DavidCarlisle I'm getting confused. Here it works sometimes. I have now tried to run this snippet about 10 times, and the dot showed up 3 times... Does it work every time for you? – mickep Sep 02 '17 at 15:23
  • @mickep tried maybe 6 or 7 times and works every time (using X display on windows/cygwin 64 texlive) – David Carlisle Sep 02 '17 at 15:34
  • I can't reproduce on Windows, but on Linux too... – TeXnician Sep 02 '17 at 16:14
  • It's amazing it still works at all, given that Knuth wrote those instructions in 1985. On my macos system (with the optional x11 install), it takes a while to start the X11 Metafont window, and it seems to ignore the very first drawdot, but once the window is open, then every showit; produces an update to the screen. And, as he goes on to explain in the next paragraph of ch.5, it's more usual to work from a file than by typing at the terminal. – Thruston Sep 02 '17 at 19:19
  • I can confirm what @Thruston said: after mf, with the sequence of instructions \relax then showit; then drawdot(35, 70); and then showit; again, I see the dot. Something to do with the interface between the terminal and X11 I guess. – ShreevatsaR Sep 03 '17 at 04:48
  • I've just had a strong sense of deja vu... I think I might vote to close this as a duplicate.. – Thruston Sep 03 '17 at 10:43
  • Why would you expect any difference between Linux and macOS? if there's a bug in the interaction between the terminal and x11 it would affect them both the same. – Thruston Sep 03 '17 at 12:31

1 Answers1

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Until this is fixed (in X?), do the following.

Before drawing anything, type openit; to open a window. If you have left the workspace and come back, type openit; showit; to redraw the current picture. (Gleaned from the METAFONTbook p. 192.)

Toothrot
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