I'm using the applet here: http://www.chessgames.com/perl/chessgame?gid=1069669 with gcjappletviewer. (As of this writing I needed a patch to make this work at all, see the classpath-patches list.) In this applet, there are some buttons whose text is cut in half. This happens for all the buttons with text on them.
I think the problem here is that the applet calls setBounds on the buttons in question. But maybe this is valid as it explicitly asks for a certain size font? FWIW the contents of the buttons do look off-center vertically.
Created attachment 9644 [details] test case demonstrating that text is not centered vertically
This is actually a GTK bug; a GtkButton doesn't center its child vertically when the child's size requisition exceeds its size allocation. I'm going to write a GTK test case and submit a bug report and patch.
I filed a bug against GTK: http://bugzilla.gnome.org/show_bug.cgi?id=315462
No feedback on this bug from the Gtk+ developers still...