My new laptop has a 4K monitor and my tool of choice for writing my Arduino books, Lyx, always displayed the toolbar icons as “so very tiny, it is hard to see the damned things!”

After much experimenting with the monitor’s scaling, fractional scaling and such like, I found QT_AUTO_SCREEN_SCALE_FACTOR which should fix things.

I tested:

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export QT_AUTO_SCREEN_SCALE_FACTOR=1
lyx &

and yes, the icons were now usable. Hooray. I just need to make this permanent.

• There is a QT Configuration application installed, but that doesn’t have any way, that is obvious, on setting environment variables. A failure!

• I added the export of QT_AUTO_SCREEN_SCALE_FACTOR to my own .bashrc startup script, which worked as long as I executed Lyx via the command line, but not from the menu. Another partial failure.

• Finally, I added a file named QT5_HIDPI_SETTING.sh to /etc/profile.d, as root, and edited the contents thusly:

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export QT_AUTO_SCREEN_SCALE_FACTOR=1

On a reboot, and obviously, afer deleting the setting from my own .bashrc file, Running Lyx from the menu gave me the desired, usable, toolbar icons and buttons.

Cheers,
Norm.