Bonjour,
Depuis ce matin sans mise à jour manuel de ma part, les charactères de GanttProject sont illisibles… J’ai mis a jour Gantt en 2-8-10 (j’étais en 2-8-5) toujours le problème. J’ai mis à jour Java, toujours le problème. J’ai ouvert une autre appli en Java et elle n’a pas se problème. Quelqu’un a rencontré le problème?
Je joins une capture pour montrer que je ne suis pas fou 
This is English speaking community. Please consider writing in English for better understanding. I am replying to your message translated with Google Translate.
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Hello,
Since this morning without manual update on my part, the characters of GanttProject are unreadable … I updated Gantt in 2-8-10 (I was 2-8-5) still the problem. I updated Java, still the problem. I opened another app in Java and it does not have a problem. Someone has encountered the problem?
I’m attaching a catch to show that I’m not crazy
It seems that something is wrong with your application font settings. Perhaps the easiest way to fix is to remove file .ganttproject from your home folder. Notice the leading dot in the file name. It may be hidden on some operating systems.
I have a similar problem and I believe that the issues is my 4K monitor. Everything works well on my other HDMI computers.
Thank you for taking the time to publish my post in the language of Shakespeare. I will try to make beautiful answers 
I’m trying your advice today and I’m making a comeback
