diff --git a/administrator/components/com_users/views/users/tmpl/modal.php b/administrator/components/com_users/views/users/tmpl/modal.php
index 1a67f0da7d7fe..c4e8fe918155b 100644
--- a/administrator/components/com_users/views/users/tmpl/modal.php
+++ b/administrator/components/com_users/views/users/tmpl/modal.php
@@ -30,8 +30,10 @@
 			<div class="btn-group pull-left">
 				<button type="submit" class="btn hasTooltip" title="<?php echo JHtml::tooltipText('JSEARCH_FILTER_SUBMIT'); ?>" data-placement="bottom"><span class="icon-search"></span></button>
 				<button type="button" class="btn hasTooltip" title="<?php echo JHtml::tooltipText('JSEARCH_FILTER_CLEAR'); ?>" data-placement="bottom" onclick="document.getElementById('filter_search').value='';this.form.submit();"><span class="icon-remove"></span></button>
-				<button type="button" class="btn button-select" data-user-value="0" data-user-name="<?php echo $this->escape(JText::_('JLIB_FORM_SELECT_USER')); ?>"
-					data-user-field="<?php echo $this->escape($field);?>"><?php echo JText::_('JOPTION_NO_USER'); ?></button>
+				<?php if ($input->get('required', 0, 'INT') != 1 ) : ?>
+					<button type="button" class="btn button-select" data-user-value="0" data-user-name="<?php echo $this->escape(JText::_('JLIB_FORM_SELECT_USER')); ?>"
+						data-user-field="<?php echo $this->escape($field);?>"><?php echo JText::_('JOPTION_NO_USER'); ?></button>
+				<?php endif; ?>
 			</div>
 			<div class="btn-group pull-right hidden-phone">
 				<label for="filter_group_id" class="element-invisible"><?php echo JText::_('COM_USERS_FILTER_USER_GROUP'); ?></label>
diff --git a/administrator/templates/isis/html/layouts/joomla/form/field/media.php b/administrator/templates/isis/html/layouts/joomla/form/field/media.php
index 85ae295eabc17..b44b66ffb077d 100644
--- a/administrator/templates/isis/html/layouts/joomla/form/field/media.php
+++ b/administrator/templates/isis/html/layouts/joomla/form/field/media.php
@@ -11,25 +11,41 @@
 
 /**
  * Layout variables
- * ---------------------
+ * -----------------
+ * @var   string   $autocomplete    Autocomplete attribute for the field.
+ * @var   boolean  $autofocus       Is autofocus enabled?
+ * @var   string   $class           Classes for the input.
+ * @var   string   $description     Description of the field.
+ * @var   boolean  $disabled        Is this field disabled?
+ * @var   string   $group           Group the field belongs to. <fields> section in form XML.
+ * @var   boolean  $hidden          Is this field hidden in the form?
+ * @var   string   $hint            Placeholder for the field.
+ * @var   string   $id              DOM id of the field.
+ * @var   string   $label           Label of the field.
+ * @var   string   $labelclass      Classes to apply to the label.
+ * @var   boolean  $multiple        Does this field support multiple values?
+ * @var   string   $name            Name of the input field.
+ * @var   string   $onchange        Onchange attribute for the field.
+ * @var   string   $onclick         Onclick attribute for the field.
+ * @var   string   $pattern         Pattern (Reg Ex) of value of the form field.
+ * @var   boolean  $readonly        Is this field read only?
+ * @var   boolean  $repeat          Allows extensions to duplicate elements.
+ * @var   boolean  $required        Is this field required?
+ * @var   integer  $size            Size attribute of the input.
+ * @var   boolean  $spellcheck      Spellcheck state for the form field.
+ * @var   string   $validate        Validation rules to apply.
+ * @var   string   $value           Value attribute of the field.
+ * @var   array    $checkedOptions  Options that will be set as checked.
+ * @var   boolean  $hasValue        Has this field a value assigned?
+ * @var   array    $options         Options available for this field.
  *
- * @var  string   $asset The asset text
- * @var  string   $authorField The label text
- * @var  integer  $authorId The author id
- * @var  string   $class The class text
- * @var  boolean  $disabled True if field is disabled
- * @var  string   $folder The folder text
- * @var  string   $id The label text
- * @var  string   $link The link text
- * @var  string   $name The name text
- * @var  string   $preview The preview image relative path
- * @var  integer  $previewHeight The image preview height
- * @var  integer  $previewWidth The image preview width
- * @var  string   $onchange  The onchange text
- * @var  boolean  $readonly True if field is readonly
- * @var  integer  $size The size text
- * @var  string   $value The value text
- * @var  string   $src The path and filename of the image
+ * @var   string   $preview         The preview image relative path
+ * @var   integer  $previewHeight   The image preview height
+ * @var   integer  $previewWidth    The image preview width
+ * @var   string   $asset           The asset text
+ * @var   string   $authorField     The label text
+ * @var   string   $folder          The folder text
+ * @var   string   $link            The link text
  */
 extract($displayData);
 
diff --git a/administrator/templates/isis/html/layouts/joomla/form/field/user.php b/administrator/templates/isis/html/layouts/joomla/form/field/user.php
index 2c609f57aa42f..bd34dce372b81 100644
--- a/administrator/templates/isis/html/layouts/joomla/form/field/user.php
+++ b/administrator/templates/isis/html/layouts/joomla/form/field/user.php
@@ -13,26 +13,51 @@
 
 /**
  * Layout variables
- * ------------------
+ * -----------------
+ * @var   string   $autocomplete    Autocomplete attribute for the field.
+ * @var   boolean  $autofocus       Is autofocus enabled?
+ * @var   string   $class           Classes for the input.
+ * @var   string   $description     Description of the field.
+ * @var   boolean  $disabled        Is this field disabled?
+ * @var   string   $group           Group the field belongs to. <fields> section in form XML.
+ * @var   boolean  $hidden          Is this field hidden in the form?
+ * @var   string   $hint            Placeholder for the field.
+ * @var   string   $id              DOM id of the field.
+ * @var   string   $label           Label of the field.
+ * @var   string   $labelclass      Classes to apply to the label.
+ * @var   boolean  $multiple        Does this field support multiple values?
+ * @var   string   $name            Name of the input field.
+ * @var   string   $onchange        Onchange attribute for the field.
+ * @var   string   $onclick         Onclick attribute for the field.
+ * @var   string   $pattern         Pattern (Reg Ex) of value of the form field.
+ * @var   boolean  $readonly        Is this field read only?
+ * @var   boolean  $repeat          Allows extensions to duplicate elements.
+ * @var   boolean  $required        Is this field required?
+ * @var   integer  $size            Size attribute of the input.
+ * @var   boolean  $spellcheck      Spellcheck state for the form field.
+ * @var   string   $validate        Validation rules to apply.
+ * @var   string   $value           Value attribute of the field.
+ * @var   array    $checkedOptions  Options that will be set as checked.
+ * @var   boolean  $hasValue        Has this field a value assigned?
+ * @var   array    $options         Options available for this field.
  *
- * @var string           $id The DOM id of the element
- * @var string           $name The name of the field
- * @var boolean          $required The required attribute
- * @var mixed            $value The value of the field (user id)
- * @var string           $class The CSS class to apply
- * @var integer          $size The ize for the input element
- * @var mixed            $groups The filtering groups (null means no filtering)
- * @var mixed            $exclude The users to exclude from the list of users
- * @var string           $onchange The script for on change event
- * @var string           $userName The user name
- * @var boolean          $readOnly Check for field read only attribute
+ * @var   string   $userName        The user name
+ * @var   mixed    $groups          The filtering groups (null means no filtering)
+ * @var   mixed    $exclude         The users to exclude from the list of users
  */
 
 // Set the link for the user selection page
-$link = 'index.php?option=com_users&amp;view=users&amp;layout=modal&amp;tmpl=component&amp;field={field-user-id}'
+$link = 'index.php?option=com_users&amp;view=users&amp;layout=modal&amp;tmpl=component&amp;required='
+	. ($required ? 1 : 0) . '&amp;field={field-user-id}'
 	. (isset($groups) ? ('&amp;groups=' . base64_encode(json_encode($groups))) : '')
 	. (isset($excluded) ? ('&amp;excluded=' . base64_encode(json_encode($excluded))) : '');
 
+// Invalidate the input value if no user selected
+if (JText::_('JLIB_FORM_SELECT_USER') == htmlspecialchars($userName, ENT_COMPAT, 'UTF-8'))
+{
+	$userName = "";
+}
+
 JHtml::script('jui/fielduser.min.js', false, true, false, false, true);
 ?>
 <?php // Create a dummy text field with the user name. ?>
@@ -47,13 +72,14 @@
 	>
 	<div class="input-append">
 		<input
-			type="text" id="<?php echo $id; ?>_name"
+			type="text" id="<?php echo $id; ?>"
 			value="<?php echo  htmlspecialchars($userName, ENT_COMPAT, 'UTF-8'); ?>"
+			placeholder="<?php echo JText::_('JLIB_FORM_SELECT_USER'); ?>"
 			readonly
-			disabled="disabled"
 			class="field-user-input-name <?php echo $class ? (string) $class : ''?>"
-			<?php echo $size ? ' size="' . (int) $size . '"' : ''; ?>/>
-		<?php if (!$readOnly) : ?>
+			<?php echo $size ? ' size="' . (int) $size . '"' : ''; ?>
+			<?php echo $required ? 'required' : ''; ?>/>
+		<?php if (!$readonly) : ?>
 			<a class="btn btn-primary button-select" title="<?php echo JText::_('JLIB_FORM_CHANGE_USER') ?>"><span class="icon-user"></span></a>
 			<?php echo JHtml::_(
 				'bootstrap.renderModal',
diff --git a/layouts/joomla/form/field/media.php b/layouts/joomla/form/field/media.php
index 73feeaa8d002b..b44d7eca36186 100644
--- a/layouts/joomla/form/field/media.php
+++ b/layouts/joomla/form/field/media.php
@@ -11,24 +11,41 @@
 
 /**
  * Layout variables
- * ---------------------
+ * -----------------
+ * @var   string   $autocomplete    Autocomplete attribute for the field.
+ * @var   boolean  $autofocus       Is autofocus enabled?
+ * @var   string   $class           Classes for the input.
+ * @var   string   $description     Description of the field.
+ * @var   boolean  $disabled        Is this field disabled?
+ * @var   string   $group           Group the field belongs to. <fields> section in form XML.
+ * @var   boolean  $hidden          Is this field hidden in the form?
+ * @var   string   $hint            Placeholder for the field.
+ * @var   string   $id              DOM id of the field.
+ * @var   string   $label           Label of the field.
+ * @var   string   $labelclass      Classes to apply to the label.
+ * @var   boolean  $multiple        Does this field support multiple values?
+ * @var   string   $name            Name of the input field.
+ * @var   string   $onchange        Onchange attribute for the field.
+ * @var   string   $onclick         Onclick attribute for the field.
+ * @var   string   $pattern         Pattern (Reg Ex) of value of the form field.
+ * @var   boolean  $readonly        Is this field read only?
+ * @var   boolean  $repeat          Allows extensions to duplicate elements.
+ * @var   boolean  $required        Is this field required?
+ * @var   integer  $size            Size attribute of the input.
+ * @var   boolean  $spellcheck      Spellcheck state for the form field.
+ * @var   string   $validate        Validation rules to apply.
+ * @var   string   $value           Value attribute of the field.
+ * @var   array    $checkedOptions  Options that will be set as checked.
+ * @var   boolean  $hasValue        Has this field a value assigned?
+ * @var   array    $options         Options available for this field.
  *
- * @var  string   $asset The asset text
- * @var  string   $authorField The label text
- * @var  integer  $authorId The author id
- * @var  string   $class The class text
- * @var  boolean  $disabled True if field is disabled
- * @var  string   $folder The folder text
- * @var  string   $id The label text
- * @var  string   $link The link text
- * @var  string   $name The name text
- * @var  string   $preview The preview image relative path
- * @var  integer  $previewHeight The image preview height
- * @var  integer  $previewWidth The image preview width
- * @var  string   $onchange  The onchange text
- * @var  boolean  $readonly True if field is readonly
- * @var  integer  $size The size text
- * @var  string   $value The value text
+ * @var   string   $preview         The preview image relative path
+ * @var   integer  $previewHeight   The image preview height
+ * @var   integer  $previewWidth    The image preview width
+ * @var   string   $asset           The asset text
+ * @var   string   $authorField     The label text
+ * @var   string   $folder          The folder text
+ * @var   string   $link            The link text
  */
 extract($displayData);
 
diff --git a/layouts/joomla/form/field/user.php b/layouts/joomla/form/field/user.php
index 2b63586c2dcab..0905e6651b2de 100644
--- a/layouts/joomla/form/field/user.php
+++ b/layouts/joomla/form/field/user.php
@@ -13,25 +13,50 @@
 
 /**
  * Layout variables
- * ------------------
+ * -----------------
+ * @var   string   $autocomplete    Autocomplete attribute for the field.
+ * @var   boolean  $autofocus       Is autofocus enabled?
+ * @var   string   $class           Classes for the input.
+ * @var   string   $description     Description of the field.
+ * @var   boolean  $disabled        Is this field disabled?
+ * @var   string   $group           Group the field belongs to. <fields> section in form XML.
+ * @var   boolean  $hidden          Is this field hidden in the form?
+ * @var   string   $hint            Placeholder for the field.
+ * @var   string   $id              DOM id of the field.
+ * @var   string   $label           Label of the field.
+ * @var   string   $labelclass      Classes to apply to the label.
+ * @var   boolean  $multiple        Does this field support multiple values?
+ * @var   string   $name            Name of the input field.
+ * @var   string   $onchange        Onchange attribute for the field.
+ * @var   string   $onclick         Onclick attribute for the field.
+ * @var   string   $pattern         Pattern (Reg Ex) of value of the form field.
+ * @var   boolean  $readonly        Is this field read only?
+ * @var   boolean  $repeat          Allows extensions to duplicate elements.
+ * @var   boolean  $required        Is this field required?
+ * @var   integer  $size            Size attribute of the input.
+ * @var   boolean  $spellcheck      Spellcheck state for the form field.
+ * @var   string   $validate        Validation rules to apply.
+ * @var   string   $value           Value attribute of the field.
+ * @var   array    $checkedOptions  Options that will be set as checked.
+ * @var   boolean  $hasValue        Has this field a value assigned?
+ * @var   array    $options         Options available for this field.
  *
- * @var string           $id The DOM id of the element
- * @var string           $name The name of the field
- * @var boolean          $required The required attribute
- * @var mixed            $value The value of the field (user id)
- * @var string           $class The CSS class to apply
- * @var integer          $size The ize for the input element
- * @var mixed            $groups The filtering groups (null means no filtering)
- * @var mixed            $exclude The users to exclude from the list of users
- * @var string           $onchange The script for on change event
- * @var string           $userName The user name
- * @var boolean          $readOnly Check for field read only attribute
+ * @var   string   $userName        The user name
+ * @var   mixed    $groups          The filtering groups (null means no filtering)
+ * @var   mixed    $exclude         The users to exclude from the list of users
  */
 
-$link = 'index.php?option=com_users&amp;view=users&amp;layout=modal&amp;tmpl=component&amp;field=' . $id
+$link = 'index.php?option=com_users&amp;view=users&amp;layout=modal&amp;tmpl=component&amp;required='
+	. ($required ? 1 : 0) . '&amp;field={field-user-id}'
 	. (isset($groups) ? ('&amp;groups=' . base64_encode(json_encode($groups))) : '')
 	. (isset($excluded) ? ('&amp;excluded=' . base64_encode(json_encode($excluded))) : '');
 
+// Invalidate the input value if no user selected
+if (JText::_('JLIB_FORM_SELECT_USER') == htmlspecialchars($userName, ENT_COMPAT, 'UTF-8'))
+{
+	$userName = "";
+}
+
 // Load the modal behavior script.
 JHtml::_('behavior.modal', 'a.modal_' . $id);
 
@@ -40,11 +65,13 @@
 <?php // Create a dummy text field with the user name. ?>
 <div class="input-append">
 	<input
-		type="text" id="<?php echo $id; ?>_name"
+		type="text" id="<?php echo $id; ?>"
 		value="<?php echo  htmlspecialchars($userName, ENT_COMPAT, 'UTF-8'); ?>"
+		placeholder="<?php echo JText::_('JLIB_FORM_SELECT_USER'); ?>"
 		readonly
-		disabled="disabled" <?php echo $size ? ' size="' . (int) $size . '"' : ''; ?> />
-	<?php if (!$readOnly) : ?>
+		<?php echo $size ? ' size="' . (int) $size . '"' : ''; ?>
+		<?php echo $required ? 'required' : ''; ?>/>
+	<?php if (!$readonly) : ?>
 		<a class="btn btn-primary modal_<?php echo $id; ?>" title="<?php echo JText::_('JLIB_FORM_CHANGE_USER'); ?>" href="<?php echo $link; ?>" rel="{handler: 'iframe', size: {x: 800, y: 500}}">
 			<span class="icon-user"></span>
 		</a>
diff --git a/libraries/cms/form/field/user.php b/libraries/cms/form/field/user.php
index e7662d8d64f5b..6d52c31334989 100644
--- a/libraries/cms/form/field/user.php
+++ b/libraries/cms/form/field/user.php
@@ -92,16 +92,10 @@ public function getLayoutData()
 			$table->name = JText::_('JLIB_FORM_SELECT_USER');
 		}
 
-		// Initialize JavaScript field attributes.
-		$onchange = (string) $this->element['onchange'];
-
 		$extraData = array(
-				'onchange'  => $onchange,
 				'userName'  => $table->name,
 				'groups'    => $this->getGroups(),
-				'excluded'  => $this->getExcluded(),
-				'readOnly'  => $this->readonly,
-				'class'     => $this->class,
+				'excluded'  => $this->getExcluded()
 		);
 
 		return array_merge($data, $extraData);
diff --git a/media/jui/js/fielduser.js b/media/jui/js/fielduser.js
index c81f3a9bc868f..ffc1f0a288d0a 100644
--- a/media/jui/js/fielduser.js
+++ b/media/jui/js/fielduser.js
@@ -123,7 +123,7 @@ function jSelectUser(element) {
 		name  = $el.data('user-name'),
 		fieldId = $el.data('user-field'),
 		$inputValue = jQuery('#' + fieldId + '_id'),
-		$inputName  = jQuery('#' + fieldId + '_name');
+		$inputName  = jQuery('#' + fieldId);
 
 	if (!$inputValue.length) {
 		// The input not found
diff --git a/media/jui/js/fielduser.min.js b/media/jui/js/fielduser.min.js
index dd6ed1d7a162b..5bc9b3e6a1279 100644
--- a/media/jui/js/fielduser.min.js
+++ b/media/jui/js/fielduser.min.js
@@ -1 +1 @@
-function jSelectUser(t){var e=jQuery(t),i=e.data("user-value"),o=e.data("user-name"),n=e.data("user-field"),a=jQuery("#"+n+"_id"),s=jQuery("#"+n+"_name");if(a.length){a.val(i).trigger("change"),s.val(o||i).trigger("change");var d,l=a.attr("data-onchange");l&&(d=new Function(l),d.call(a[0])),jModalClose()}}!function(t){"use strict";t.fieldUser=function(e,i){this.options=t.extend({},t.fieldUser.defaults,i),this.$container=t(e),this.$modal=this.$container.find(this.options.modal),this.$modalBody=this.$modal.children(".modal-body"),this.$input=this.$container.find(this.options.input),this.$inputName=this.$container.find(this.options.inputName),this.$buttonSelect=this.$container.find(this.options.buttonSelect),this.$buttonSelect.on("click",this.modalOpen.bind(this)),this.$modal.on("hide",this.removeIframe.bind(this));var o,n=this.$input.attr("data-onchange");n&&(o=new Function(n),this.$input.on("change",o.bind(this.$input)))},t.fieldUser.prototype.modalOpen=function(){var e=t("<iframe>",{name:"field-user-modal",src:this.options.url.replace("{field-user-id}",this.$input.attr("id")),width:this.options.modalWidth,height:this.options.modalHeight});this.$modalBody.append(e),this.$modal.modal("show"),t("body").addClass("modal-open");var i=this;e.load(function(){var e=t(this).contents();e.on("click",".button-select",function(){i.setValue(t(this).data("user-value"),t(this).data("user-name")),i.modalClose(),t("body").removeClass("modal-open")})})},t.fieldUser.prototype.modalClose=function(){this.$modal.modal("hide"),this.$modalBody.empty(),t("body").removeClass("modal-open")},t.fieldUser.prototype.removeIframe=function(){this.$modalBody.empty(),t("body").removeClass("modal-open")},t.fieldUser.prototype.setValue=function(t,e){this.$input.val(t).trigger("change"),this.$inputName.val(e||t).trigger("change")},t.fieldUser.defaults={buttonSelect:".button-select",input:".field-user-input",inputName:".field-user-input-name",modal:".modal",url:"index.php?option=com_users&view=users&layout=modal&tmpl=component",modalWidth:"100%",modalHeight:"300px"},t.fn.fieldUser=function(){return this.each(function(){var e=t(this),i=e.data("fieldUser");if(!i){var o=o||{},n=e.data();for(var a in n)n.hasOwnProperty(a)&&(o[a]=n[a]);i=new t.fieldUser(this,o),e.data("fieldUser",i)}})},t(document).ready(function(){t(".field-user-wrapper").fieldUser()})}(jQuery);
\ No newline at end of file
+function jSelectUser(t){var e=jQuery(t),i=e.data("user-value"),o=e.data("user-name"),n=e.data("user-field"),a=jQuery("#"+n+"_id"),s=jQuery("#"+n);if(a.length){a.val(i).trigger("change"),s.val(o||i).trigger("change");var d,l=a.attr("data-onchange");l&&(d=new Function(l),d.call(a[0])),jModalClose()}}!function(t){"use strict";t.fieldUser=function(e,i){this.options=t.extend({},t.fieldUser.defaults,i),this.$container=t(e),this.$modal=this.$container.find(this.options.modal),this.$modalBody=this.$modal.children(".modal-body"),this.$input=this.$container.find(this.options.input),this.$inputName=this.$container.find(this.options.inputName),this.$buttonSelect=this.$container.find(this.options.buttonSelect),this.$buttonSelect.on("click",this.modalOpen.bind(this)),this.$modal.on("hide",this.removeIframe.bind(this));var o,n=this.$input.attr("data-onchange");n&&(o=new Function(n),this.$input.on("change",o.bind(this.$input)))},t.fieldUser.prototype.modalOpen=function(){var e=t("<iframe>",{name:"field-user-modal",src:this.options.url.replace("{field-user-id}",this.$input.attr("id")),width:this.options.modalWidth,height:this.options.modalHeight});this.$modalBody.append(e),this.$modal.modal("show"),t("body").addClass("modal-open");var i=this;e.load(function(){var e=t(this).contents();e.on("click",".button-select",function(){i.setValue(t(this).data("user-value"),t(this).data("user-name")),i.modalClose(),t("body").removeClass("modal-open")})})},t.fieldUser.prototype.modalClose=function(){this.$modal.modal("hide"),this.$modalBody.empty(),t("body").removeClass("modal-open")},t.fieldUser.prototype.removeIframe=function(){this.$modalBody.empty(),t("body").removeClass("modal-open")},t.fieldUser.prototype.setValue=function(t,e){this.$input.val(t).trigger("change"),this.$inputName.val(e||t).trigger("change")},t.fieldUser.defaults={buttonSelect:".button-select",input:".field-user-input",inputName:".field-user-input-name",modal:".modal",url:"index.php?option=com_users&view=users&layout=modal&tmpl=component",modalWidth:"100%",modalHeight:"300px"},t.fn.fieldUser=function(){return this.each(function(){var e=t(this),i=e.data("fieldUser");if(!i){var o=o||{},n=e.data();for(var a in n)n.hasOwnProperty(a)&&(o[a]=n[a]);i=new t.fieldUser(this,o),e.data("fieldUser",i)}})},t(document).ready(function(){t(".field-user-wrapper").fieldUser()})}(jQuery);
\ No newline at end of file
diff --git a/templates/protostar/html/layouts/joomla/form/field/contenthistory.php b/templates/protostar/html/layouts/joomla/form/field/contenthistory.php
index d082f44724c74..1812a210a3efd 100644
--- a/templates/protostar/html/layouts/joomla/form/field/contenthistory.php
+++ b/templates/protostar/html/layouts/joomla/form/field/contenthistory.php
@@ -11,10 +11,36 @@
 
 /**
  * Layout variables
- * ---------------------
+ * -----------------
+ * @var   string   $autocomplete    Autocomplete attribute for the field.
+ * @var   boolean  $autofocus       Is autofocus enabled?
+ * @var   string   $class           Classes for the input.
+ * @var   string   $description     Description of the field.
+ * @var   boolean  $disabled        Is this field disabled?
+ * @var   string   $group           Group the field belongs to. <fields> section in form XML.
+ * @var   boolean  $hidden          Is this field hidden in the form?
+ * @var   string   $hint            Placeholder for the field.
+ * @var   string   $id              DOM id of the field.
+ * @var   string   $label           Label of the field.
+ * @var   string   $labelclass      Classes to apply to the label.
+ * @var   boolean  $multiple        Does this field support multiple values?
+ * @var   string   $name            Name of the input field.
+ * @var   string   $onchange        Onchange attribute for the field.
+ * @var   string   $onclick         Onclick attribute for the field.
+ * @var   string   $pattern         Pattern (Reg Ex) of value of the form field.
+ * @var   boolean  $readonly        Is this field read only?
+ * @var   boolean  $repeat          Allows extensions to duplicate elements.
+ * @var   boolean  $required        Is this field required?
+ * @var   integer  $size            Size attribute of the input.
+ * @var   boolean  $spellcheck       Spellcheck state for the form field.
+ * @var   string   $validate        Validation rules to apply.
+ * @var   string   $value           Value attribute of the field.
+ * @var   array    $checkedOptions  Options that will be set as checked.
+ * @var   boolean  $hasValue        Has this field a value assigned?
+ * @var   array    $options         Options available for this field.
  *
- * @var  string   $link The link for the content history page
- * @var  string   $label The label text
+ * @var   string   $link            The link for the content history page
+ * @var   string   $label           The label text
  */
 extract($displayData);
 
diff --git a/templates/protostar/html/layouts/joomla/form/field/media.php b/templates/protostar/html/layouts/joomla/form/field/media.php
index 20a50515615a3..c28d1b14b3c14 100644
--- a/templates/protostar/html/layouts/joomla/form/field/media.php
+++ b/templates/protostar/html/layouts/joomla/form/field/media.php
@@ -11,25 +11,41 @@
 
 /**
  * Layout variables
- * ---------------------
+ * -----------------
+ * @var   string   $autocomplete    Autocomplete attribute for the field.
+ * @var   boolean  $autofocus       Is autofocus enabled?
+ * @var   string   $class           Classes for the input.
+ * @var   string   $description     Description of the field.
+ * @var   boolean  $disabled        Is this field disabled?
+ * @var   string   $group           Group the field belongs to. <fields> section in form XML.
+ * @var   boolean  $hidden          Is this field hidden in the form?
+ * @var   string   $hint            Placeholder for the field.
+ * @var   string   $id              DOM id of the field.
+ * @var   string   $label           Label of the field.
+ * @var   string   $labelclass      Classes to apply to the label.
+ * @var   boolean  $multiple        Does this field support multiple values?
+ * @var   string   $name            Name of the input field.
+ * @var   string   $onchange        Onchange attribute for the field.
+ * @var   string   $onclick         Onclick attribute for the field.
+ * @var   string   $pattern         Pattern (Reg Ex) of value of the form field.
+ * @var   boolean  $readonly        Is this field read only?
+ * @var   boolean  $repeat          Allows extensions to duplicate elements.
+ * @var   boolean  $required        Is this field required?
+ * @var   integer  $size            Size attribute of the input.
+ * @var   boolean  $spellcheck      Spellcheck state for the form field.
+ * @var   string   $validate        Validation rules to apply.
+ * @var   string   $value           Value attribute of the field.
+ * @var   array    $checkedOptions  Options that will be set as checked.
+ * @var   boolean  $hasValue        Has this field a value assigned?
+ * @var   array    $options         Options available for this field.
  *
- * @var  string   $asset The asset text
- * @var  string   $authorField The label text
- * @var  integer  $authorId The author id
- * @var  string   $class The class text
- * @var  boolean  $disabled True if field is disabled
- * @var  string   $folder The folder text
- * @var  string   $id The label text
- * @var  string   $link The link text
- * @var  string   $name The name text
- * @var  string   $preview The preview image relative path
- * @var  integer  $previewHeight The image preview height
- * @var  integer  $previewWidth The image preview width
- * @var  string   $onchange  The onchange text
- * @var  boolean  $readonly True if field is readonly
- * @var  integer  $size The size text
- * @var  string   $value The value text
- * @var  string   $src The path and filename of the image
+ * @var   string   $preview         The preview image relative path
+ * @var   integer  $previewHeight   The image preview height
+ * @var   integer  $previewWidth    The image preview width
+ * @var   string   $asset           The asset text
+ * @var   string   $authorField     The label text
+ * @var   string   $folder          The folder text
+ * @var   string   $link            The link text
  */
 extract($displayData);
 
diff --git a/templates/protostar/html/layouts/joomla/form/field/user.php b/templates/protostar/html/layouts/joomla/form/field/user.php
index 34c0d2c931b65..f9b906d0bc0fc 100644
--- a/templates/protostar/html/layouts/joomla/form/field/user.php
+++ b/templates/protostar/html/layouts/joomla/form/field/user.php
@@ -13,26 +13,51 @@
 
 /**
  * Layout variables
- * ------------------
+ * -----------------
+ * @var   string   $autocomplete    Autocomplete attribute for the field.
+ * @var   boolean  $autofocus       Is autofocus enabled?
+ * @var   string   $class           Classes for the input.
+ * @var   string   $description     Description of the field.
+ * @var   boolean  $disabled        Is this field disabled?
+ * @var   string   $group           Group the field belongs to. <fields> section in form XML.
+ * @var   boolean  $hidden          Is this field hidden in the form?
+ * @var   string   $hint            Placeholder for the field.
+ * @var   string   $id              DOM id of the field.
+ * @var   string   $label           Label of the field.
+ * @var   string   $labelclass      Classes to apply to the label.
+ * @var   boolean  $multiple        Does this field support multiple values?
+ * @var   string   $name            Name of the input field.
+ * @var   string   $onchange        Onchange attribute for the field.
+ * @var   string   $onclick         Onclick attribute for the field.
+ * @var   string   $pattern         Pattern (Reg Ex) of value of the form field.
+ * @var   boolean  $readonly        Is this field read only?
+ * @var   boolean  $repeat          Allows extensions to duplicate elements.
+ * @var   boolean  $required        Is this field required?
+ * @var   integer  $size            Size attribute of the input.
+ * @var   boolean  $spellcheck      Spellcheck state for the form field.
+ * @var   string   $validate        Validation rules to apply.
+ * @var   string   $value           Value attribute of the field.
+ * @var   array    $checkedOptions  Options that will be set as checked.
+ * @var   boolean  $hasValue        Has this field a value assigned?
+ * @var   array    $options         Options available for this field.
  *
- * @var string           $id The DOM id of the element
- * @var string           $name The name of the field
- * @var boolean          $required The required attribute
- * @var mixed            $value The value of the field (user id)
- * @var string           $class The CSS class to apply
- * @var integer          $size The ize for the input element
- * @var mixed            $groups The filtering groups (null means no filtering)
- * @var mixed            $exclude The users to exclude from the list of users
- * @var string           $onchange The script for on change event
- * @var string           $userName The user name
- * @var boolean          $readOnly Check for field read only attribute
+ * @var   string   $userName        The user name
+ * @var   mixed    $groups          The filtering groups (null means no filtering)
+ * @var   mixed    $exclude         The users to exclude from the list of users
  */
 
 // Set the link for the user selection page
-$link = 'index.php?option=com_users&amp;view=users&amp;layout=modal&amp;tmpl=component&amp;field={field-user-id}'
+$link = 'index.php?option=com_users&amp;view=users&amp;layout=modal&amp;tmpl=component&amp;required='
+	. ($required ? 1 : 0) . '&amp;field={field-user-id}'
 	. (isset($groups) ? ('&amp;groups=' . base64_encode(json_encode($groups))) : '')
 	. (isset($excluded) ? ('&amp;excluded=' . base64_encode(json_encode($excluded))) : '');
 
+// Invalidate the input value if no user selected
+if (JText::_('JLIB_FORM_SELECT_USER') == htmlspecialchars($userName, ENT_COMPAT, 'UTF-8'))
+{
+	$userName = "";
+}
+
 JHtml::script('jui/fielduser.min.js', false, true, false, false, true);
 ?>
 <?php // Create a dummy text field with the user name. ?>
@@ -47,13 +72,14 @@
 	>
 	<div class="input-append">
 		<input
-			type="text" id="<?php echo $id; ?>_name"
+			type="text" id="<?php echo $id; ?>"
 			value="<?php echo  htmlspecialchars($userName, ENT_COMPAT, 'UTF-8'); ?>"
+			placeholder="<?php echo JText::_('JLIB_FORM_SELECT_USER'); ?>"
 			readonly
-			disabled="disabled"
 			class="field-user-input-name <?php echo $class ? (string) $class : ''?>"
-			<?php echo $size ? ' size="' . (int) $size . '"' : ''; ?>/>
-		<?php if (!$readOnly) : ?>
+			<?php echo $size ? ' size="' . (int) $size . '"' : ''; ?>
+			<?php echo $required ? 'required' : ''; ?>/>
+		<?php if (!$readonly) : ?>
 			<a class="btn btn-primary button-select" title="<?php echo JText::_('JLIB_FORM_CHANGE_USER') ?>"><span class="icon-user"></span></a>
 			<?php echo JHtml::_(
 				'bootstrap.renderModal',