Index: t3lib/class.t3lib_tcemain.php
===================================================================
--- t3lib/class.t3lib_tcemain.php	(revision 6485)
+++ t3lib/class.t3lib_tcemain.php	(working copy)
@@ -1524,7 +1524,7 @@
 					);
 				break;
 				case 'db':
-					$valueArray = $this->checkValue_group_select_processDBdata($valueArray,$tcaFieldConf,$id,$status,'group', $table);
+					$valueArray = $this->checkValue_group_select_processDBdata($valueArray,$tcaFieldConf,$id,$status,'group', $table, $field);
 				break;
 			}
 		}
@@ -1535,13 +1535,13 @@
 				$this->remapStackRecords[$table][$id] = array('remapStackIndex' => count($this->remapStack));
 				$this->remapStack[] = array(
 					'func' => 'checkValue_group_select_processDBdata',
-					'args' => array($valueArray,$tcaFieldConf,$id,$status,'select',$table),
+					'args' => array($valueArray,$tcaFieldConf,$id,$status,'select',$table,$field),
 					'pos' => array('valueArray' => 0, 'tcaFieldConf' => 1, 'id' => 2, 'table' => 5),
 					'field' => $field
 				);
 				$unsetResult = true;
 			} else {
-				$valueArray = $this->checkValue_group_select_processDBdata($valueArray,$tcaFieldConf,$id,$status,'select', $table);
+				$valueArray = $this->checkValue_group_select_processDBdata($valueArray,$tcaFieldConf,$id,$status,'select', $table, $field);
 			}
 		}
 
@@ -1637,6 +1637,7 @@
 					} else {
 						$theFileValues=t3lib_div::trimExplode(',',$curValue,1);
 					}
+					$currentFilesForHistory = implode(',', $theFileValues);
 
 						// DELETE files: If existing files were found, traverse those and register files for deletion which has been removed:
 					if (count($theFileValues))	{
@@ -1721,6 +1722,15 @@
 				}
 				if ($status=='update')	{
 					$dbAnalysis->writeMM($tcaFieldConf['MM'],$id,0);
+					$newFiles = implode(',', $dbAnalysis->getValueArray());
+					list(,,$recFieldName) = explode(':', $recFID);
+					if ($currentFilesForHistory != $newFiles) {
+						$this->mmHistoryRecords[$currentTable . ':' . $id]['oldRecord'][$recFieldName] = $currentFilesForHistory;
+						$this->mmHistoryRecords[$currentTable . ':' . $id]['newRecord'][$recFieldName] = $newFiles;
+					} else {
+						$this->mmHistoryRecords[$currentTable . ':' . $id]['oldRecord'][$currentField] = '';
+						$this->mmHistoryRecords[$currentTable . ':' . $id]['newRecord'][$currentField] = '';
+					}
 				} else {
 					$this->dbAnalysisStore[] = array($dbAnalysis, $tcaFieldConf['MM'], $id, 0);	// This will be traversed later to execute the actions
 				}
@@ -2175,20 +2185,35 @@
 	 * @param	string		Status string ('update' or 'new')
 	 * @param	string		The type, either 'select', 'group' or 'inline'
 	 * @param	string		Table name, needs to be passed to t3lib_loadDBGroup
+	 * @param	string		field name, needs to be set for writing to sys_history
 	 * @return	array		Modified value array
 	 */
-	function checkValue_group_select_processDBdata($valueArray,$tcaFieldConf,$id,$status,$type,$currentTable)	{
+	function checkValue_group_select_processDBdata($valueArray,$tcaFieldConf,$id,$status,$type,$currentTable,$currentField)	{
 		$tables = $type=='group'?$tcaFieldConf['allowed']:$tcaFieldConf['foreign_table'].','.$tcaFieldConf['neg_foreign_table'];
 		$prep = $type=='group'?$tcaFieldConf['prepend_tname']:$tcaFieldConf['neg_foreign_table'];
+		$newRelations = implode(',', $valueArray);
 
 		$dbAnalysis = t3lib_div::makeInstance('t3lib_loadDBGroup');
 		/* @var $dbAnalysis t3lib_loadDBGroup */
 		$dbAnalysis->registerNonTableValues=$tcaFieldConf['allowNonIdValues'] ? 1 : 0;
-		$dbAnalysis->start(implode(',',$valueArray),$tables, '', 0, $currentTable, $tcaFieldConf);
+		$dbAnalysis->start($newRelations, $tables, '', 0, $currentTable, $tcaFieldConf);
 
 		if ($tcaFieldConf['MM'])	{
 			if ($status=='update')	{
+				$oldRelations_dbAnalysis = t3lib_div::makeInstance('t3lib_loadDBGroup');
+				/* @var $oldRelations_dbAnalysis t3lib_loadDBGroup */
+				$oldRelations_dbAnalysis->registerNonTableValues=$tcaFieldConf['allowNonIdValues'] ? 1 : 0;
+					// db analysis with $id will initialize with the existing relations
+				$oldRelations_dbAnalysis->start('', $tables, $tcaFieldConf['MM'], $id, $currentTable, $tcaFieldConf);
+				$oldRelations = implode(',', $oldRelations_dbAnalysis->getValueArray());
 				$dbAnalysis->writeMM($tcaFieldConf['MM'],$id,$prep);
+				if ($oldRelations != $newRelations) {
+					$this->mmHistoryRecords[$currentTable . ':' . $id]['oldRecord'][$currentField] = $oldRelations;
+					$this->mmHistoryRecords[$currentTable . ':' . $id]['newRecord'][$currentField] = $newRelations;
+				} else {
+					$this->mmHistoryRecords[$currentTable . ':' . $id]['oldRecord'][$currentField] = '';
+					$this->mmHistoryRecords[$currentTable . ':' . $id]['newRecord'][$currentField] = '';
+				}
 			} else {
 				$this->dbAnalysisStore[] = array($dbAnalysis,$tcaFieldConf['MM'],$id,$prep,$currentTable);	// This will be traversed later to execute the actions
 			}
@@ -6442,13 +6467,23 @@
 				// Unset the fields which are similar:
 			foreach($fieldArray as $col => $val)	{
 				if (
-						!strcmp($val,$currentRecord[$col]) ||	// Unset fields which matched exactly.
-						($cRecTypes[$col]=='int' && $currentRecord[$col]==0 && !strcmp($val,''))	// Now, a situation where TYPO3 tries to put an empty string into an integer field, we should not strcmp the integer-zero and '', but rather accept them to be similar.
-					)	{
+					!$GLOBALS['TCA'][$table]['columns'][$col]['config']['MM'] && // Do not unset MM relation fields, since equality of the MM count doesn't always mean that relations haven't changed.
+					( !strcmp($val,$currentRecord[$col]) ||	// Unset fields which matched exactly.
+					  ($cRecTypes[$col]=='int' && $currentRecord[$col]==0 && !strcmp($val,''))	// Now, a situation where TYPO3 tries to put an empty string into an integer field, we should not strcmp the integer-zero and '', but rather accept them to be similar.
+					)
+				) {
 					unset($fieldArray[$col]);
 				} else {
-					$this->historyRecords[$table.':'.$id]['oldRecord'][$col] = $currentRecord[$col];
-					$this->historyRecords[$table.':'.$id]['newRecord'][$col] = $fieldArray[$col];
+					if (!isset($this->mmHistoryRecords[$table.':'.$id]['oldRecord'][$col])) {
+						$this->historyRecords[$table.':'.$id]['oldRecord'][$col] = $currentRecord[$col];
+					} elseif ($this->mmHistoryRecords[$table.':'.$id]['oldRecord'][$col] != '') {
+						$this->historyRecords[$table.':'.$id]['oldRecord'][$col] = $this->mmHistoryRecords[$table.':'.$id]['oldRecord'][$col];
+					}
+					if (!isset($this->mmHistoryRecords[$table.':'.$id]['newRecord'][$col])) {
+						$this->historyRecords[$table.':'.$id]['newRecord'][$col] = $fieldArray[$col];
+					} elseif ($this->mmHistoryRecords[$table.':'.$id]['newRecord'][$col] != '') {
+						$this->historyRecords[$table.':'.$id]['newRecord'][$col] = $this->mmHistoryRecords[$table.':'.$id]['newRecord'][$col];
+					}
 				}
 			}
 		} else {	// If the current record does not exist this is an error anyways and we just return an empty array here.