I am using Arch Linux, and recently I found that my fonts are little different after upgrade.

In DBeaver, the monospace font shows this:

This causes the monospace doesn’t follow the same width. And I found that, the default “Monospace” doesn’t use DejaVu Sans Mono anymore after the recent upgrade.

After looking some solutions, I tried edit ~/.conf/fontconfig/fonts.conf according to this this one.

<match target="pattern">
    <test qual="any" name="family">
        <string>monospace</string>
    </test>
    <edit name="family" mode="assign" binding="same">
        <string>DejaVu Sans Mono</string>
    </edit>
</match>

The above solution solves the monospace in most applications like Mousepad and DBeaver.

When downloading the files contain Chinese or Japanese characters using JDownloader in Linux (for my case, Arch Linux), I found that all the Chinese or Japanese characters are shown with boxes. There are a lot of suggested solutions I found from Internet, especially adding !font=Dialog to the language file. I also tried to edit the fontconfig.properties file, adding path to JAVA_FONTS, etc. But all the solutions do not work.

So, my solution is, just change the user interface style to non-Synthetica style, eg, Substance or Light. Both types of style work well, allow me to see the file names with correct characters. Problem solved.