unfortunately I created the gantt chart for my research proposal in ganttproject and have only now realized, that you cant zoom out to more then a monthly view. This makes it impossible to display a 5 year plan meaningfully on a dinA4 page. Hitting up google found people more then a decade back with the same problem. Please think about adding it, the lack of this feature meant for me, that i had to start over with a different tool.
There is also an open issue for this
edit: I should also add, that this especially frustrating as ganttproject is often the first project to be mentioned when looking for gantt on Linux. The lack of such a basic feature made me curse myself for not using the Microsoft version.