Bug 39244 modifiersChanged() hook not called in NewTypeWizardPage [code manipulation]
The modifiersChanged() hook in NewTypeWizardPage is not being called when a modifier radio-button is selected (public/default/private/protected), it is only being called if a check box is selected (abstract/final/static). I suspect a missing "else if" clause in typePageDialogFieldChanged() in NewTypeWizardPage is the culprit. As such am unable to extend NewTypeWizardPage and validate modifier settings (working on custom "class" wizard extension).
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/wizards/NewTypeWizardPage.java
int modifiers= getModifiers();
		buf.append(Flags.toString(modifiers));
		if (modifiers != 0) {
			buf.append(' ');
		}
		buf.append(fIsClass ? "class " : "interface "); 
		buf.append(getTypeName());
		writeSuperClass(buf, imports);
		writeSuperInterfaces(buf, imports);	
		buf.append('{');
		buf.append(lineDelimiter);
		buf.append(lineDelimiter);
		buf.append('}');
		buf.append(lineDelimiter);
		return buf.toString();
	}
	/**
	 * @deprecated Overwrite createTypeMembers(IType, IImportsManager, IProgressMonitor) instead
	 */		
	protected void createTypeMembers(IType newType, IImportsStructure imports, IProgressMonitor monitor) throws CoreException {
		
	}
	
	/**
	 * Hook method that gets called from <code>createType</code> to support adding of 
	 * unanticipated methods, fields, and inner types to the created type.
	 * <p>
	 * Implementers can use any methods defined on <code>IType</code> to manipulate the
	 * new type.
	 * </p>