added a large amount of missing documentation

ButtonDropdown.php

@@ -39,6 +39,7 @@ class ButtonDropdown extends Widget
 	public $label = 'Button';
 	/**
 	 * @var array the HTML attributes of the button.
+	 * See [[\yii\helpers\Html::renderTagAttributes()]] for details on how attributes are being rendered.
 	 */
 	public $options = [];
 	/**

NavBar.php

@@ -42,13 +42,17 @@ class NavBar extends Widget
 	/**
 	 * @var array the HTML attributes for the widget container tag. The following special options are recognized:
 	 *
-	 * - tag: string, defaults to "nav", the name of the container tag
+	 * - tag: string, defaults to "nav", the name of the container tag.
+	 *
+	 * See [[\yii\helpers\Html::renderTagAttributes()]] for details on how attributes are being rendered.
 	 */
 	public $options = [];
 	/**
 	 * @var array the HTML attributes for the container tag. The following special options are recognized:
 	 *
-	 * - tag: string, defaults to "div", the name of the container tag
+	 * - tag: string, defaults to "div", the name of the container tag.
+	 *
+	 * See [[\yii\helpers\Html::renderTagAttributes()]] for details on how attributes are being rendered.
 	 */
 	public $containerOptions = [];
 	/**
@@ -63,6 +67,7 @@ class NavBar extends Widget
 	public $brandUrl;
 	/**
 	 * @var array the HTML attributes of the brand link.
+	 * See [[\yii\helpers\Html::renderTagAttributes()]] for details on how attributes are being rendered.
 	 */
 	public $brandOptions = [];
 	/**
@@ -76,6 +81,7 @@ class NavBar extends Widget
 	public $renderInnerContainer = true;
 	/**
 	 * @var array the HTML attributes of the inner container.
+	 * See [[\yii\helpers\Html::renderTagAttributes()]] for details on how attributes are being rendered.
 	 */
 	public $innerContainerOptions = [];
 

Progress.php

@@ -60,7 +60,7 @@ use yii\helpers\Html;
 class Progress extends Widget
 {
 	/**
-	 * @var string the button label
+	 * @var string the button label.
 	 */
 	public $label;
 	/**
@@ -68,7 +68,8 @@ class Progress extends Widget
 	 */
 	public $percent = 0;
 	/**
-	 * @var array the HTML attributes of the bar
+	 * @var array the HTML attributes of the bar.
+	 * See [[\yii\helpers\Html::renderTagAttributes()]] for details on how attributes are being rendered.
 	 */
 	public $barOptions = [];
 	/**
@@ -84,6 +85,7 @@ class Progress extends Widget
 	 *     // optional, array, additional HTML attributes for the bar tag
 	 *     'options' => [],
 	 * ]
+	 * ```
 	 */
 	public $bars;
 

Tabs.php

@@ -75,16 +75,20 @@ class Tabs extends Widget
 	 * by the "options" set in individual [[items]]. The following special options are recognized:
 	 *
 	 * - tag: string, defaults to "div", the tag name of the item container tags.
+	 *
+	 * See [[\yii\helpers\Html::renderTagAttributes()]] for details on how attributes are being rendered.
 	 */
 	public $itemOptions = [];
 	/**
 	 * @var array list of HTML attributes for the header container tags. This will be overwritten
 	 * by the "headerOptions" set in individual [[items]].
+	 * See [[\yii\helpers\Html::renderTagAttributes()]] for details on how attributes are being rendered.
 	 */
 	public $headerOptions = [];
 	/**
 	 * @var array list of HTML attributes for the tab header link tags. This will be overwritten
 	 * by the "linkOptions" set in individual [[items]].
+	 * See [[\yii\helpers\Html::renderTagAttributes()]] for details on how attributes are being rendered.
 	 */
 	public $linkOptions = [];
 	/**

Widget.php

@@ -21,6 +21,7 @@ class Widget extends \yii\base\Widget
 {
 	/**
 	 * @var array the HTML attributes for the widget container tag.
+	 * See [[\yii\helpers\Html::renderTagAttributes()]] for details on how attributes are being rendered.
 	 */
 	public $options = [];
 	/**