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
return new String[] {
			PREF_NEWLINE_OPENING_BRACES, PREF_NEWLINE_CONTROL_STATEMENT, PREF_NEWLINE_CLEAR_ALL,
			PREF_NEWLINE_ELSE_IF, PREF_NEWLINE_EMPTY_BLOCK, PREF_LINE_SPLIT,
			PREF_STYLE_COMPACT_ASSIGNEMENT, PREF_TAB_CHAR, PREF_TAB_SIZE, PREF_SPACE_CASTEXPRESSION
		};	
	}	
	protected Control createContents(Composite parent) {
		fPixelConverter= new PixelConverter(parent);
		
		int textWidth= fPixelConverter.convertWidthInCharsToPixels(6);
		
		GridLayout layout= new GridLayout();
		layout.marginHeight= 0;
		layout.marginWidth= 0;
		
		Composite composite= new Composite(parent, SWT.NONE);
		composite.setLayout(layout);
		
		TabFolder folder= new TabFolder(composite, SWT.NONE);
		folder.setLayout(new TabFolderLayout());	
		folder.setLayoutData(new GridData(GridData.FILL_BOTH));
		
		String[] insertNotInsert= new String[] { INSERT, DO_NOT_INSERT };
		
		layout= new GridLayout();
		layout.numColumns= 2;
		
		Composite newlineComposite= new Composite(folder, SWT.NULL);
		newlineComposite.setLayout(layout);
		String label= PreferencesMessages.getString("CodeFormatterPreferencePage.newline_opening_braces.label");