Index: admin_templates/incs/form_blocks.tpl
===================================================================
--- admin_templates/incs/form_blocks.tpl	(revision 14544)
+++ admin_templates/incs/form_blocks.tpl	(working copy)
@@ -381,6 +381,35 @@
 	</inp2:m_RenderElement>
 </inp2:m_DefineElement>
 
+<inp2:m_DefineElement name="inp_edit_date_time_combined" class="">
+	<inp2:m_RenderElement design="form_row" pass_params="1">
+		<td class="control-cell">
+			<input type="text" name="<inp2:{$prefix}_InputName field='$field'/>" id="<inp2:{$prefix}_InputName field='$field'/>" value="<inp2:{$prefix}_Field field='$field' format='_input_'/>" tabindex="<inp2:m_get param='tab_index'/>" size="<inp2:{$prefix}_Format field='$field' input_format='1' edit_size='edit_size'/>" class="<inp2:m_param name='class'/>" datepickerIcon="<inp2:m_ProjectBase/>core/admin_templates/img/calendar_icon.gif"/>
+
+			<img src="img/calendar_icon.gif" id="cal_img_<inp2:{$prefix}_InputName field="{$field}"/>"
+					     style="cursor: pointer; margin-right: 5px"
+					     title="Date selector"
+					/>
+				<span class="small">(<inp2:{$prefix}_Format field="$field" input_format="1" human="true"/>)</span>
+
+			<script type="text/javascript">
+				Calendar.setup({
+			        inputField	:	"<inp2:{$prefix}_InputName field='{$field}'/>",
+			        ifFormat	:	Calendar.phpDateFormat("<inp2:{$prefix}_Format field='{$field}' input_format='1'/>"),
+			        button		:	"cal_img_<inp2:{$prefix}_InputName field='{$field}'/>",
+			        align		:	"br",
+			        singleClick	:	true,
+			        showsTime	:	true,
+			        weekNumbers	:	false,
+			        firstDay	:	<inp2:m_GetConfig var="FirstDayOfWeek"/>
+				});
+			</script>
+
+			<input type="hidden" name="<inp2:{$prefix}_InputName field='{$field}_combined'/>" value="1"/>
+		</td>
+	</inp2:m_RenderElement>
+</inp2:m_DefineElement>
+
 <inp2:m_DefineElement name="textarea_field_caption_element">
 	<inp2:m_RenderElement name="default_field_caption_element" pass_params="1"/>
 
Index: kernel/utility/formatters/date_formatter.php
===================================================================
--- kernel/utility/formatters/date_formatter.php	(revision 14544)
+++ kernel/utility/formatters/date_formatter.php	(working copy)
@@ -37,7 +37,7 @@
 	function SetMixedFormat(&$field_options, &$format, $type)
 	{
 		if (!isset($field_options[$type])) {
-			// default value is date+sepatator+time
+			// default value is date+separator+time
 			$field_options[$type] = '_regional_DateTimeFormat';
 		}
 
@@ -94,6 +94,15 @@
 		}
 	}
 
+	/**
+	 * The method is supposed to alter config options or configure object in some way based on its usage of formatters
+	 * The methods is called for every field with formatter defined when configuring item.
+	 * Could be used for adding additional VirtualFields to an object required by some special Formatter
+	 *
+	 * @param string $field_name
+	 * @param array $field_options
+	 * @param kDBBase $object
+	 */
 	function PrepareOptions($field_name, &$field_options, &$object)
 	{
 		list ($display_format, $input_format) = $this->GetSeparateFormats($field_options, 'mixed');
@@ -104,9 +113,12 @@
 			$field_options['use_timezone'] = true;
 		}
 
-		$add_fields = Array();
+		// 1. add field to indicate, that date is already combined into one field
+		$add_fields = Array(
+			$field_name . '_combined' => Array ('type' => 'int', 'default' => 0),
+		);
 
-		// 1. add DATE virtual field
+		// 2. add DATE virtual field
 		$opts = Array('master_field' => $field_name, 'formatter' => 'kDateFormatter', 'format' => $display_format['date'], 'input_format' => $input_format['date']);
 
 		$copy_options = Array ('default', 'required', 'use_timezone', 'error_msgs');
@@ -118,7 +130,7 @@
 
 		$add_fields[$field_name.'_date'] = $opts;
 
-		// 2. add TIME virtual field
+		// 3. add TIME virtual field
 		$opts['format'] = $display_format['time'];
 		$opts['input_format'] = $input_format['time'];
 		$add_fields[$field_name.'_time'] = $opts;
@@ -132,7 +144,7 @@
 		}
 
 		if ( !isset($object->VirtualFields[$field_name]) ) {
-			// adding caluclated field to format date directly in the query
+			// adding calculated field to format date directly in the query
 			if ( !isset($object->CalculatedFields)  || !is_array($object->CalculatedFields) ) {
 				$object->CalculatedFields = Array();
 			}
@@ -149,6 +161,15 @@
 		$object->setVirtualFields($add_fields);
 	}
 
+	/**
+	 * Used for split fields like timestamp -> date, time
+	 * Called from DBItem to update sub fields values after loading item
+	 *
+	 * @param string $field
+	 * @param string $value
+	 * @param Array $options
+	 * @param kDBItem $object
+	 */
 	function UpdateSubFields($field, $value, &$options, &$object)
 	{
 		if ( $sub_fields = getArrayValue($options, 'sub_fields') ) {
@@ -160,11 +181,29 @@
 		}
 	}
 
+	/**
+	 * Used for split fields like timestamp -> date, time
+	 * Called from DBItem Validate (before validation) to get back master field value from its sub_fields
+	 *
+	 * @param string $field
+	 * @param mixed $value
+	 * @param Array $options
+	 * @param kDBItem $object
+	 */
 	function UpdateMasterFields($field, $value, &$options, &$object)
 	{
-		// when in master field - set own value from sub_fields
-		if ( $sub_fields = getArrayValue($options, 'sub_fields') ) {
-			// if date is not empty, but time is empty - set time to 0, otherwise master field fomratter will complain
+		$sub_fields = getArrayValue($options, 'sub_fields');
+		$master_field = getArrayValue($options, 'master_field');
+
+		if ( $master_field ) {
+			// when in one of sub_fields - call update for master_field to update its value from sub_fields [are you following ? :) ]
+			$opt = $object->GetFieldOptions($master_field);
+			$this->UpdateMasterFields($master_field, null, $opt, $object);
+		}
+		elseif ( $sub_fields && !$object->GetDBField($field . '_combined') ) {
+			// when in master field - set own value from sub_fields
+
+			// if date is not empty, but time is empty - set time to 0, otherwise master field formatter will complain
 			// when we have only date field on form, we need time hidden field always empty, don't ask me why!
 			if ($object->GetDBField($sub_fields['date']) != '' && $object->GetDBField($sub_fields['time']) == '') {
 				$empty_time = getArrayValue($options,'empty_time');
@@ -186,14 +225,17 @@
 
 			$object->SetField($field, $object->GetField($sub_fields['date'], $input_format['date']).$options['date_time_separator'].$object->GetField($sub_fields['time'], $input_format['time']));
 		}
-		// when in one of sub_fields - call update for master_field to update its value from sub_fields [are you following ? :) ]
-		elseif ($master_field = getArrayValue($options, 'master_field') ) {
-			$opt = $object->GetFieldOptions($master_field);
-			$this->UpdateMasterFields($master_field, null, $opt, $object);
-		}
 	}
 
-//function Format($value, $options, &$errors)
+	/**
+	 * Formats given field value
+	 *
+	 * @param string $value
+	 * @param string $field_name
+	 * @param kDBItem $object
+	 * @param string $format
+	 * @return string
+	 */
 	function Format($value, $field_name, &$object, $format=null)
 	{
 		if ( is_null($value) ) return '';