Fix requirements being inconsistently included.

code/GridFieldAddExistingSearchButton.php

@@ -17,8 +17,7 @@ class GridFieldAddExistingSearchButton implements
 	}
 
 	public function getHTMLFragments($grid) {
-		Requirements::css('gridfieldextensions/css/GridFieldExtensions.css');
+		GridFieldExtensions::include_requirements();
-		Requirements::javascript('gridfieldextensions/javascript/GridFieldExtensions.js');
 
 		$data = new ArrayData(array(
 			'Link'  => $grid->Link('add-existing-search')

code/GridFieldAddNewMultiClass.php

@@ -135,6 +135,8 @@ class GridFieldAddNewMultiClass implements GridField_HTMLProvider, GridField_URL
 			return array();
 		}
 
+		GridFieldExtensions::include_requirements();
+
 		$field = new DropdownField(sprintf('%s[ClassName]', __CLASS__), '', $classes);
 		$field->setEmptyString(_t('GridFieldExtensions.SELECTTYPETOCREATE', '(Select type to create)'));
 		$field->addExtraClass('no-change-track');

code/GridFieldEditableColumns.php

@@ -45,6 +45,7 @@ class GridFieldEditableColumns extends GridFieldDataColumns implements
 	}
 
 	public function getHTMLFragments($grid) {
+		GridFieldExtensions::include_requirements();
 		$grid->addExtraClass('ss-gridfield-editable');
 	}
 

code/GridFieldExtensions.php

@@ -0,0 +1,12 @@
+<?php
+/**
+ * Utility functions for the grid fields extension module.
+ */
+class GridFieldExtensions {
+
+	public static function include_requirements() {
+		Requirements::css('gridfieldextensions/css/GridFieldExtensions.css');
+		Requirements::javascript('gridfieldextensions/javascript/GridFieldExtensions.js');
+	}
+
+}

code/GridFieldOrderableRows.php

@@ -86,9 +86,7 @@ class GridFieldOrderableRows extends RequestHandler implements
 	}
 
 	public function getHTMLFragments($field) {
-		Requirements::css('gridfieldextensions/css/GridFieldExtensions.css');
+		GridFieldExtensions::include_requirements();
-		Requirements::javascript('gridfieldextensions/javascript/GridFieldExtensions.js');
-
 		$field->addExtraClass('ss-gridfield-orderable');
 	}