I’m running on Ubuntu Resolute Racoon, and after a recent update, my x3270 sessions connecting to z/OS all look out of focus, or like my glasses are dirty.

I think that something has changed in the fonts that are used, or my screen sizes, so when data is displayed it is having to fake the font.

I define a 3270 using a command like

x3270 -model 5 -title mstcon mstcon@localhost:3270  &

where mstcon is the short name.

I needed to be able to change the size of the 3270 screen, so the fonts were clear.

Third attempt at fixing it.

The easiest way of fixing the problem was to use

export DPI=240
x3270a -model 5 -title mstcon mstcon@localhost:3270  &

This may all be connected with X11 being removed from Ubuntu 26.04, and Ubuntu using Wayland instead. The XWayland code making the system look like X11 may have a couple of hickups.

The information below is from my journey to getting a readable screen.

What is the size of my screen?

You can use the wmctrl command to display information about the screen. wmctrl interacts with the X11 window manager.

wmctrl -l -G

This lists the geometry of all the screens

0x00600169 -1 396  478  2496 1520 ColinNew mstcon
0x00c00169 -1 794  702  2496 1582 ColinNew colin
0x00e00169 -1 794  764  2496 1520 ColinNew tso

Where

• ColinNew is the name of my userid
• mstcon is the name of my x3270 window
• 396 478 is the position of the top left corner of the window,
• 2496 1520 is the width and height of the window

You can change the configuration using

 wmctrl -r  colin  -e  1,744,618,2496,1582 

You can grab the edges of the x3270 window, and make adjust the size till it looks right, then use the wmctrl -l -G to capture the geometry – and update your wmctrl … -e command.

Or you can do it with X3270

x3270 ... -geom 2496x1582+711+618 ...

Where -geom is -geometry widthxheight+x+y .

The font size jumps!

There are a set of fonts, as you change the size of the screen, for example make it half an inch narrower, at some point it may reconfigure, and suddenly use a smaller font (with lots of space around the content). You should size the window so it is wide enough and high enough for the font size, without wasting space around the content.

My glasses?

I also had a new pair of glasses, and have to position my head to be able to get the windows in focus. Because I keep my 3270 sessions at the top of my screens, I have to tilt my head back slightly!

Update

I did the following commands

sudo apt install fonts-3270
sudo apt install xfonts-x3270-misc
sudo sudo fc-cache -f -v

And x3270 suddenly got better with readable fonts etc..