Bug 31395 Child window of Preferences dialog centers between screens
On the Preferences->Java->Code Generation->Names tab, the Edit button opens a dialog that is split between multiple monitors, instead of centering on the main Preference window like the rest of its child windows do.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/TodoTaskConfigurationBlock.java
for (int i= 0; i < list.size(); i++) {
			if (i > 0) {
				tags.append(',');
				prios.append(',');
			}
			TodoTask elem= (TodoTask) list.get(i);
			tags.append(elem.name);
			prios.append(elem.priority);
		}
		fWorkingValues.put(PREF_COMPILER_TASK_TAGS, tags.toString());
		fWorkingValues.put(PREF_COMPILER_TASK_PRIORITIES, prios.toString());
	}
		
	private void doTodoButtonPressed(int index) {
		TodoTask edited= null;
		if (index != 0) {
			edited= (TodoTask) fTodoTasksList.getSelectedElements().get(0);
		}
		
		TodoTaskInputDialog dialog= new TodoTaskInputDialog(getShell(), edited, fTodoTasksList.getElements());
		if (dialog.open() == TodoTaskInputDialog.OK) {
			if (edited != null) {
				fTodoTasksList.replaceElement(edited, dialog.getResult());
			} else {
				fTodoTasksList.addElement(dialog.getResult());
			}
		}
	}
}