I recently created product modeladmin as below, what i want is to show another inline button like 'Update URL' next to category dropdown on change event, please see the attached screenshot

class Product extends DataObject {

private static $db = array(
'URLSegment' => 'Varchar(100)',
'Title' => 'Varchar(255)',
'MetaTitle' => 'Varchar(255)',
'MetaDescription' => 'Varchar(255)',
'Content' => 'HTMLText',
"SortOrder" => "Int",
"Size" => "Text",
);

private static $defaults = array(
'Title'=>'New Item',
'URLSegment' => 'new-item'
);

private static $has_one = array(
'ProductCategory' => 'ProductCategory',
'Image1' => 'Image',
'Image2' => 'Image',
'Image3' => 'Image'
);

//The class of the page which will list this DataObject
//private static $listing_page_class = 'ProductCategory';
//Class Naming (optional but reccomended)
private static $singular_name = "Product";
private static $plural_name = "Products";

private static $default_sort = '"Title" ASC';

static $summary_fields = array(
"ProductThumbnail" => "Image",
"Title" => "Name",
"Size" => "Size",
'ProductCategory.Title' => 'Category'
);

/*
static $searchable_fields = array(
'Title',
'Size',
'Content'=> array('title' => 'Content'),
'ProductCategoryID' => array('title' => 'Product Category')
);
*/

static $field_labels = array(
'Title' => 'Product Name'
);

public function getCMSFields()
{
$fields = parent::getCMSFields();

/ /$fields->addFieldToTab('Root.Main', new TextField('Title','Name'));

//Remove Scafolded fields
$fields->removeFieldFromTab('Root.Main', 'URLSegment');
$fields->removeFieldFromTab('Root.Main', 'MetaTitle');
$fields->removeFieldFromTab('Root.Main', 'MetaDescription');

$fields->addFieldToTab('Root.Main', new TextField('Title'));

if($this->ID)
{
$urlsegment = new SiteTreeURLSegmentField("URLSegment", $this->fieldLabel('URLSegment'));
//$urlsegment->setURLPrefix($prefix);

$helpText = _t('SiteTreeURLSegmentField.HelpChars', ' Special characters are automatically converted or removed.');
$urlsegment->setHelpText($helpText);
$fields->addFieldToTab('Root.Main', $urlsegment);
}

$fields->addFieldToTab('Root.Main', new HTMLEditorField('Content'));

$fields->addFieldToTab('Root.Main',new ToggleCompositeField('Metadata', 'Metadata',
array(
new TextField("MetaTitle", $this->fieldLabel('MetaTitle')),
new TextareaField("MetaDescription", $this->fieldLabel('MetaDescription'))
)
));

$fields->removeFieldFromTab("Root.Main","ProductCategoryID");

$fields->addFieldsToTab('Root.Main', array(
DropdownField::create('ProductCategoryID', _t("Product.CATEGORY", "Category"), $this->categoryoptions())
,
), 'Content');

$fields->addFieldToTab('Root.ProductImages', $uploadField = new UploadField('Image1','Main Product Image'));
$uploadField->setFolderName('Products/'.$this->URLSegment);
$fields->addFieldToTab('Root.ProductImages', $uploadField = new UploadField('Image2','Second Product Image'));
$uploadField->setFolderName('Products/'.$this->URLSegment);
$fields->addFieldToTab('Root.ProductImages', $uploadField = new UploadField('Image3','Third Product Image'));
$uploadField->setFolderName('Products/'.$this->URLSegment);
//$uploadField->setConfig('fileEditFields', 'priorityField');
//$uploadField->FolderName = 'Uploads/'.'member-photos/'.($this->Title);
$fields->addFieldToTab('Root.Main', new TextField('Size'));

$fields->removeFieldsFromTab('Root.Main', array('SortOrder'));

return $fields;
}

public function getProductThumbnail() {
if ($Image = $this->Image1()->ID) {
return $this->Image1()->SetWidth(100);
} else {
return '(No Image)';
}
}
/**
* Helper function for generating list of categories to select from.
* @return array categories
*/
private function categoryoptions() {
$categories = ProductCategory::get()->map('ID', 'NestedTitle')->toArray();
$categories = array(
0 => _t("SiteTree.PARENTTYPE_ROOT", "Top-level page")
) + $categories;

return $categories;
}

}