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/CodeFormatterConfigurationBlock.java
BufferedReader rin= null;
		try {
			rin= new BufferedReader(new InputStreamReader(getClass().getResourceAsStream(filename)));
			String line;
			while ((line= rin.readLine()) != null) {
				if (btxt.length() > 0) {
					btxt.append(separator);
				}
				btxt.append(line);
			}
		} catch (IOException io) {
			JavaPlugin.log(io);
		} finally {
			if (rin != null) {
				try { rin.close(); } catch (IOException e) {}
			}
		}
		return btxt.toString();
	}
	private void updatePreview() {
		ICodeFormatter formatter= ToolFactory.createDefaultCodeFormatter(fWorkingValues);
		fPreviewDocument.set(formatter.format(fPreviewText, 0, null, "\n")); 
	}	
		
	private IStatus validatePositiveNumber(String number) {
		StatusInfo status= new StatusInfo();
		if (number.length() == 0) {
			status.setError(PreferencesMessages.getString("CodeFormatterPreferencePage.empty_input")); 
		} else {
			try {