Hello,
I searched the forum for a possibilty of formating the text of task and found this: Comment out gan document / Formatting / Trancparency where you say:
I’m enjoying using Ganttproject but was wondering if you are planning to implement the possibility of changing the formating of the text of a task. (e.g. bold, italic, underline, highlight, color, etc).
It is already possible to put smiley and I think that having the same font size across Ganttproject is nice, but having the name of the main task bold would be a plus.