diff --git a/administrator/components/com_categories/models/category.php b/administrator/components/com_categories/models/category.php
index 1fdd3ba12b93e..85a0796327f55 100644
--- a/administrator/components/com_categories/models/category.php
+++ b/administrator/components/com_categories/models/category.php
@@ -449,6 +449,8 @@ protected function preprocessForm(JForm $form, $data, $group = 'content')
 					$field->addAttribute('label', $language->title);
 					$field->addAttribute('translate_label', 'false');
 					$field->addAttribute('extension', $extension);
+					$field->addAttribute('select', 'true');
+					$field->addAttribute('new', 'true');
 					$field->addAttribute('edit', 'true');
 					$field->addAttribute('clear', 'true');
 				}
diff --git a/administrator/components/com_categories/models/fields/modal/category.php b/administrator/components/com_categories/models/fields/modal/category.php
index 034920dabb716..f1ae9a2d9d82f 100644
--- a/administrator/components/com_categories/models/fields/modal/category.php
+++ b/administrator/components/com_categories/models/fields/modal/category.php
@@ -42,91 +42,63 @@ protected function getInput()
 			$extension = (string) JFactory::getApplication()->input->get('extension', 'com_content');
 		}
 
-		$allowEdit  = ((string) $this->element['edit'] == 'true') ? true : false;
-		$allowClear = ((string) $this->element['clear'] != 'false') ? true : false;
+		$allowNew    = ((string) $this->element['new'] == 'true');
+		$allowEdit   = ((string) $this->element['edit'] == 'true');
+		$allowClear  = ((string) $this->element['clear'] != 'false');
+		$allowSelect = ((string) $this->element['select'] != 'false');
 
-		// Load language
+		// Load language.
 		JFactory::getLanguage()->load('com_categories', JPATH_ADMINISTRATOR);
 
 		// The active category id field.
 		$value = (int) $this->value > 0 ? (int) $this->value : '';
 
-		// Build the script.
-		$script = array();
+		// Create the modal id.
+		$modalId = 'Category_' . $this->id;
 
-		// Select button script
-		$script[] = '	function jSelectCategory_' . $this->id . '(id, title, object) {';
-		$script[] = '		document.getElementById("' . $this->id . '_id").value = id;';
-		$script[] = '		document.getElementById("' . $this->id . '_name").value = title;';
+		// Add the modal field script to the document head.
+		JHtml::_('jquery.framework');
+		JHtml::_('script', 'system/modal-fields.js', false, true);
 
-		if ($allowEdit)
-		{
-			$script[] = '		if (id == "' . (int) $this->value . '") {';
-			$script[] = '			jQuery("#' . $this->id . '_edit").removeClass("hidden");';
-			$script[] = '		} else {';
-			$script[] = '			jQuery("#' . $this->id . '_edit").addClass("hidden");';
-			$script[] = '		}';
-		}
-
-		if ($allowClear)
+		// Script to proxy the select modal function to the modal-fields.js file.
+		if ($allowSelect)
 		{
-			$script[] = '		jQuery("#' . $this->id . '_clear").removeClass("hidden");';
-		}
+			static $scriptSelect = null;
 
-		$script[] = '		jQuery("#categorySelect' . $this->id . 'Modal").modal("hide");';
-		$script[] = '	}';
-
-		// Edit button script
-		$script[] = '	function jEditCategory_' . $value . '(title) {';
-		$script[] = '		document.getElementById("' . $this->id . '_name").value = title;';
-		$script[] = '	}';
+			if (is_null($scriptSelect))
+			{
+				$scriptSelect = array();
+			}
 
-		// Clear button script
-		static $scriptClear;
+			if (!isset($scriptSelect[$this->id]))
+			{
+				JFactory::getDocument()->addScriptDeclaration("
+				function jSelectCategory_" . $this->id . "(id, title, object) {
+					window.processModalSelect('Category', '" . $this->id . "', id, title, '', object);
+				}
+				");
 
-		if ($allowClear && !$scriptClear)
-		{
-			$scriptClear = true;
-
-			$script[] = '	function jClearCategory(id) {';
-			$script[] = '		document.getElementById(id + "_id").value = "";';
-			$script[] = '		document.getElementById(id + "_name").value = "'
-				. htmlspecialchars(JText::_('COM_CATEGORIES_SELECT_A_CATEGORY', true), ENT_COMPAT, 'UTF-8') . '";';
-			$script[] = '		jQuery("#"+id + "_clear").addClass("hidden");';
-			$script[] = '		if (document.getElementById(id + "_edit")) {';
-			$script[] = '			jQuery("#"+id + "_edit").addClass("hidden");';
-			$script[] = '		}';
-			$script[] = '		return false;';
-			$script[] = '	}';
+				$scriptSelect[$this->id] = true;
+			}
 		}
 
-		// Add the script to the document head.
-		JFactory::getDocument()->addScriptDeclaration(implode("\n", $script));
-
 		// Setup variables for display.
-		$html = array();
-
-		$linkCategories = 'index.php?option=com_categories&view=categories&layout=modal&tmpl=component'
-			. '&extension=' . $extension
-			. '&function=jSelectCategory_' . $this->id;
-
-		$linkCategory   = 'index.php?option=com_categories&view=category&layout=modal&tmpl=component'
-			. '&task=category.edit'
-			. '&function=jEditCategory_' . $value;
+		$linkCategories = 'index.php?option=com_categories&view=categories&layout=modal&tmpl=component&' . JSession::getFormToken() . '=1'
+			. '&extension=' . $extension;
+		$linkCategory  = 'index.php?option=com_categories&view=category&layout=modal&tmpl=component&' . JSession::getFormToken() . '=1'
+			. '&extension=' . $extension;
+		$modalTitle    = JText::_('COM_CATEGORIES_CHANGE_CATEGORY');
 
 		if (isset($this->element['language']))
 		{
 			$linkCategories .= '&forcedLanguage=' . $this->element['language'];
 			$linkCategory   .= '&forcedLanguage=' . $this->element['language'];
-			$modalTitle = JText::_('COM_CATEGORIES_CHANGE_CATEGORY') . ' — ' . $this->element['label'];
-		}
-		else
-		{
-			$modalTitle = JText::_('COM_CATEGORIES_CHANGE_CATEGORY');
+			$modalTitle     .= ' — ' . $this->element['label'];
 		}
 
-		$urlSelect = $linkCategories . '&' . JSession::getFormToken() . '=1';
-		$urlEdit   = $linkCategory . '&id=' . $value . '&' . JSession::getFormToken() . '=1';
+		$urlSelect = $linkCategories . '&function=jSelectCategory_' . $this->id;
+		$urlEdit   = $linkCategory . '&task=category.edit&id=\' + document.getElementById("' . $this->id . '_id").value + \'';
+		$urlNew    = $linkCategory . '&task=category.add';
 
 		if ($value)
 		{
@@ -147,101 +119,150 @@ protected function getInput()
 			}
 		}
 
-		if (empty($title))
+		$title = empty($title) ? JText::_('COM_CATEGORIES_SELECT_A_CATEGORY') : htmlspecialchars($title, ENT_QUOTES, 'UTF-8');
+
+		// The current category display field.
+		$html  = '<span class="input-append">';
+		$html .= '<input class="input-medium" id="' . $this->id . '_name" type="text" value="' . $title . '" disabled="disabled" size="35" />';
+
+		// Select category button.
+		if ($allowSelect)
 		{
-			$title = JText::_('COM_CATEGORIES_SELECT_A_CATEGORY', true);
+			$html .= '<a'
+				. ' class="btn hasTooltip' . ($value ? ' hidden' : '') . '"'
+				. ' id="' . $this->id . '_select"'
+				. ' data-toggle="modal"'
+				. ' role="button"'
+				. ' href="#ModalSelect' . $modalId . '"'
+				. ' title="' . JHtml::tooltipText('COM_CATEGORIES_CHANGE_CATEGORY') . '">'
+				. '<span class="icon-file"></span> ' . JText::_('JSELECT')
+				. '</a>';
 		}
 
-		$title = htmlspecialchars($title, ENT_QUOTES, 'UTF-8');
+		// New category button.
+		if ($allowNew)
+		{
+			$html .= '<a'
+				. ' class="btn hasTooltip' . ($value ? ' hidden' : '') . '"'
+				. ' id="' . $this->id . '_new"'
+				. ' data-toggle="modal"'
+				. ' role="button"'
+				. ' href="#ModalNew' . $modalId . '"'
+				. ' title="' . JHtml::tooltipText('COM_CATEGORIES_NEW_CATEGORY') . '">'
+				. '<span class="icon-new"></span> ' . JText::_('JACTION_CREATE')
+				. '</a>';
+		}
 
-		// The current category display field.
-		$html[] = '<span class="input-append">';
-		$html[] = '<input class="input-medium" id="' . $this->id . '_name" type="text" value="' . $title . '" disabled="disabled" size="35" />';
-
-		// Select category button
-		$html[] = '<a'
-			. ' class="btn hasTooltip"'
-			. ' data-toggle="modal"'
-			. ' role="button"'
-			. ' href="#categorySelect' . $this->id . 'Modal"'
-			. ' title="' . JHtml::tooltipText('COM_CATEGORIES_CHANGE_CATEGORY') . '">'
-			. '<span class="icon-file"></span> ' . JText::_('JSELECT')
-			. '</a>';
-
-		// Edit category button
+		// Edit category button.
 		if ($allowEdit)
 		{
-			$html[] = '<a'
+			$html .= '<a'
 				. ' class="btn hasTooltip' . ($value ? '' : ' hidden') . '"'
 				. ' id="' . $this->id . '_edit"'
 				. ' data-toggle="modal"'
 				. ' role="button"'
-				. ' href="#categoryEdit' . $value . 'Modal"'
+				. ' href="#ModalEdit' . $modalId . '"'
 				. ' title="' . JHtml::tooltipText('COM_CATEGORIES_EDIT_CATEGORY') . '">'
 				. '<span class="icon-edit"></span> ' . JText::_('JACTION_EDIT')
 				. '</a>';
 		}
 
-		// Clear category button
+		// Clear category button.
 		if ($allowClear)
 		{
-			$html[] = '<button'
+			$html .= '<a'
 				. ' class="btn' . ($value ? '' : ' hidden') . '"'
 				. ' id="' . $this->id . '_clear"'
-				. ' onclick="return jClearCategory(\'' . $this->id . '\')">'
+				. ' href="#"'
+				. ' onclick="window.processModalParent(\'' . $this->id . '\'); return false;">'
 				. '<span class="icon-remove"></span>' . JText::_('JCLEAR')
-				. '</button>';
+				. '</a>';
 		}
 
-		$html[] = '</span>';
-
-		// Select category modal
-		$html[] = JHtml::_(
-			'bootstrap.renderModal',
-			'categorySelect' . $this->id . 'Modal',
-			array(
-				'title'       => $modalTitle,
-				'url'         => $urlSelect,
-				'height'      => '400px',
-				'width'       => '800px',
-				'bodyHeight'  => '70',
-				'modalWidth'  => '80',
-				'footer'      => '<a type="button" class="btn" data-dismiss="modal" aria-hidden="true">'
-						. JText::_("JLIB_HTML_BEHAVIOR_CLOSE") . '</a>',
-			)
-		);
-
-		// Edit category modal
-		$html[] = JHtml::_(
-			'bootstrap.renderModal',
-			'categoryEdit' . $value . 'Modal',
-			array(
-				'title'       => JText::_('COM_CATEGORIES_EDIT_CATEGORY'),
-				'backdrop'    => 'static',
-				'keyboard'    => false,
-				'closeButton' => false,
-				'url'         => $urlEdit,
-				'height'      => '400px',
-				'width'       => '800px',
-				'bodyHeight'  => '70',
-				'modalWidth'  => '80',
-				'footer'      => '<a type="button" class="btn" data-dismiss="modal" aria-hidden="true"'
-						. ' onclick="jQuery(\'#categoryEdit' . $value . 'Modal iframe\').contents().find(\'#closeBtn\').click();">'
-						. JText::_("JLIB_HTML_BEHAVIOR_CLOSE") . '</a>'
-						. '<button type="button" class="btn btn-primary" aria-hidden="true"'
-						. ' onclick="jQuery(\'#categoryEdit' . $value . 'Modal iframe\').contents().find(\'#saveBtn\').click();">'
-						. JText::_("JSAVE") . '</button>'
-						. '<button type="button" class="btn btn-success" aria-hidden="true"'
-						. ' onclick="jQuery(\'#categoryEdit' . $value . 'Modal iframe\').contents().find(\'#applyBtn\').click();">'
-						. JText::_("JAPPLY") . '</button>',
-			)
-		);
+		$html .= '</span>';
+
+		// Select category modal.
+		if ($allowSelect)
+		{
+			$html .= JHtml::_(
+				'bootstrap.renderModal',
+				'ModalSelect' . $modalId,
+				array(
+					'title'       => $modalTitle,
+					'url'         => $urlSelect,
+					'height'      => '400px',
+					'width'       => '800px',
+					'bodyHeight'  => '70',
+					'modalWidth'  => '80',
+					'footer'      => '<a role="button" class="btn" data-dismiss="modal" aria-hidden="true">' . JText::_("JLIB_HTML_BEHAVIOR_CLOSE") . '</a>',
+				)
+			);
+		}
+
+		// New category modal.
+		if ($allowNew)
+		{
+			$html .= JHtml::_(
+				'bootstrap.renderModal',
+				'ModalNew' . $modalId,
+				array(
+					'title'       => JText::_('COM_CATEGORIES_NEW_CATEGORY'),
+					'backdrop'    => 'static',
+					'keyboard'    => false,
+					'closeButton' => false,
+					'url'         => $urlNew,
+					'height'      => '400px',
+					'width'       => '800px',
+					'bodyHeight'  => '70',
+					'modalWidth'  => '80',
+					'footer'      => '<a role="button" class="btn" aria-hidden="true"'
+							. ' onclick="window.processModalEdit(this, \'' . $this->id . '\', \'add\', \'category\', \'cancel\', \'item-form\'); return false;">'
+							. JText::_("JLIB_HTML_BEHAVIOR_CLOSE") . '</a>'
+							. '<a role="button" class="btn btn-primary" aria-hidden="true"'
+							. ' onclick="window.processModalEdit(this, \'' . $this->id . '\', \'add\', \'category\', \'save\', \'item-form\'); return false;">'
+							. JText::_("JSAVE") . '</a>'
+							. '<a role="button" class="btn btn-success" aria-hidden="true"'
+							. ' onclick="window.processModalEdit(this, \'' . $this->id . '\', \'add\', \'category\', \'apply\', \'item-form\'); return false;">'
+							. JText::_("JAPPLY") . '</a>',
+				)
+			);
+		}
+
+		// Edit category modal.
+		if ($allowEdit)
+		{
+			$html .= JHtml::_(
+				'bootstrap.renderModal',
+				'ModalEdit' . $modalId,
+				array(
+					'title'       => JText::_('COM_CATEGORIES_EDIT_CATEGORY'),
+					'backdrop'    => 'static',
+					'keyboard'    => false,
+					'closeButton' => false,
+					'url'         => $urlEdit,
+					'height'      => '400px',
+					'width'       => '800px',
+					'bodyHeight'  => '70',
+					'modalWidth'  => '80',
+					'footer'      => '<a role="button" class="btn" aria-hidden="true"'
+							. ' onclick="window.processModalEdit(this, \'' . $this->id . '\', \'edit\', \'category\', \'cancel\', \'item-form\'); return false;">'
+							. JText::_("JLIB_HTML_BEHAVIOR_CLOSE") . '</a>'
+							. '<a role="button" class="btn btn-primary" aria-hidden="true"'
+							. ' onclick="window.processModalEdit(this, \'' . $this->id . '\', \'edit\', \'category\', \'save\', \'item-form\'); return false;">'
+							. JText::_("JSAVE") . '</a>'
+							. '<a role="button" class="btn btn-success" aria-hidden="true"'
+							. ' onclick="window.processModalEdit(this, \'' . $this->id . '\', \'edit\', \'category\', \'apply\', \'item-form\'); return false;">'
+							. JText::_("JAPPLY") . '</a>',
+				)
+			);
+		}
 
 		// Note: class='required' for client side validation
 		$class = $this->required ? ' class="required modal-value"' : '';
 
-		$html[] = '<input type="hidden" id="' . $this->id . '_id"' . $class . ' name="' . $this->name . '" value="' . $value . '" />';
+		$html .= '<input type="hidden" id="' . $this->id . '_id"' . $class . ' data-required="' . (int) $this->required . '" name="' . $this->name . '"'
+			. '" data-text="' . htmlspecialchars(JText::_('COM_CATEGORIES_SELECT_A_CATEGORY', true), ENT_COMPAT, 'UTF-8') . '" value="' . $value . '" />';
 
-		return implode("\n", $html);
+		return $html;
 	}
 }
diff --git a/administrator/components/com_categories/views/category/tmpl/edit.php b/administrator/components/com_categories/views/category/tmpl/edit.php
index f354d814381fc..10eeb20451bc1 100644
--- a/administrator/components/com_categories/views/category/tmpl/edit.php
+++ b/administrator/components/com_categories/views/category/tmpl/edit.php
@@ -32,6 +32,7 @@
 			' . $this->form->getField("description")->save() . '
 			Joomla.submitform(task, document.getElementById("item-form"));
 
+			// @deprecated 4.0  The following js is not needed since __DEPLOY_VERSION__.
 			if (task !== "category.apply")
 			{
 				window.parent.jQuery("#categoryEdit' . $this->item->id . 'Modal").modal("hide");
@@ -99,6 +100,7 @@
 
 		<?php echo $this->form->getInput('extension'); ?>
 		<input type="hidden" name="task" value="" />
+		<input type="hidden" name="forcedLanguage" value="<?php echo $input->get('forcedLanguage', '', 'cmd'); ?>" />
 		<?php echo JHtml::_('form.token'); ?>
 	</div>
 </form>
diff --git a/administrator/components/com_categories/views/category/tmpl/modal.php b/administrator/components/com_categories/views/category/tmpl/modal.php
index 28203343ec637..54256456f031c 100644
--- a/administrator/components/com_categories/views/category/tmpl/modal.php
+++ b/administrator/components/com_categories/views/category/tmpl/modal.php
@@ -11,6 +11,7 @@
 
 JHtml::_('bootstrap.tooltip', '.hasTooltip', array('placement' => 'bottom'));
 
+// @deprecated 4.0 the function parameter, the inline js and the buttons are not needed since __DEPLOY_VERSION__.
 $function  = JFactory::getApplication()->input->getCmd('function', 'jEditCategory_' . (int) $this->item->id);
 
 // Function to update input title when changed
diff --git a/administrator/components/com_categories/views/category/view.html.php b/administrator/components/com_categories/views/category/view.html.php
index 6ca4f8ca972fe..445c1a14250ca 100644
--- a/administrator/components/com_categories/views/category/view.html.php
+++ b/administrator/components/com_categories/views/category/view.html.php
@@ -81,9 +81,25 @@ public function display($tpl = null)
 		JFactory::getApplication()->input->set('hidemainmenu', true);
 
 		if ($this->getLayout() == 'modal')
+		{
+			// If we are forcing a language in modal (used for associations).
+			if ($forcedLanguage = JFactory::getApplication()->input->get('forcedLanguage', '', 'cmd'))
+			{
+				// Set the language field to the forcedLanguage and disable changing it.
+				$this->form->setValue('language', null, $forcedLanguage);
+				$this->form->setFieldAttribute('language', 'readonly', 'true');
+
+				// Only allow to select categories with All language or with the forced language.
+				$this->form->setFieldAttribute('parent_id', 'language', '*,' . $forcedLanguage);
+
+				// Only allow to select tags with All language or with the forced language.
+				$this->form->setFieldAttribute('tags', 'language', '*,' . $forcedLanguage);
+			}
+		}
+		// If not in associations modal, block the language change if in edit modal, language not All and associations enabled.
+		elseif ($this->item->id && $this->form->getValue('language', null, '*') != '*' && JLanguageAssociations::isEnabled())
 		{
 			$this->form->setFieldAttribute('language', 'readonly', 'true');
-			$this->form->setFieldAttribute('parent_id', 'readonly', 'true');
 		}
 
 		$this->addToolbar();
diff --git a/administrator/language/en-GB/en-GB.com_categories.ini b/administrator/language/en-GB/en-GB.com_categories.ini
index 047e1705ff281..2d9d3ece8f95a 100644
--- a/administrator/language/en-GB/en-GB.com_categories.ini
+++ b/administrator/language/en-GB/en-GB.com_categories.ini
@@ -67,6 +67,7 @@ COM_CATEGORIES_N_ITEMS_TRASHED="%d categories successfully trashed."
 COM_CATEGORIES_N_ITEMS_TRASHED_1="%d category successfully trashed."
 COM_CATEGORIES_N_ITEMS_UNPUBLISHED="%d categories successfully unpublished."
 COM_CATEGORIES_N_ITEMS_UNPUBLISHED_1="%d category successfully unpublished."
+COM_CATEGORIES_NEW_CATEGORY="New Category"
 COM_CATEGORIES_NO_ITEM_SELECTED="Please first make a selection from the list."
 COM_CATEGORIES_PATH_LABEL="Category Path"
 COM_CATEGORIES_REBUILD_FAILURE="Failed rebuilding Categories tree data."