diff --git a/application/dashboardlayout.class.inc.php b/application/dashboardlayout.class.inc.php
index 4a17ed070..c99d6d7d8 100644
--- a/application/dashboardlayout.class.inc.php
+++ b/application/dashboardlayout.class.inc.php
@@ -105,13 +105,14 @@ abstract class DashboardLayoutMultiCol extends DashboardLayout
 	{
 		// Trim the list of cells to remove the invisible/empty ones at the end of the array
 		$aCells = $this->TrimCellsArray($aCells);
-		
+
 		$oPage->add('<table style="width:100%;table-layout:fixed;"><tbody>');
 		$iCellIdx = 0;
 		$fColSize = 100 / $this->iNbCols;
 		$sStyle = $bEditMode ? 'border: 1px #ccc dashed; width:'.$fColSize.'%;' : 'width: '.$fColSize.'%;';
 		$sClass = $bEditMode ? 'layout_cell edit_mode' : 'dashboard';
 		$iNbRows = ceil(count($aCells) / $this->iNbCols);
+
 		for($iRows = 0; $iRows < $iNbRows; $iRows++)
 		{
 			$oPage->add('<tr>');
@@ -129,7 +130,8 @@ abstract class DashboardLayoutMultiCol extends DashboardLayout
 						{
 							if ($oDashlet->IsVisible())
 							{
-								$sDashletId = $oDashlet->GetID();
+								$sDashletIdOrig = $oDashlet->GetID();
+								$sDashletId = $sDashletIdOrig;
 								if(strpos($sDashletId, 'IDrow') === false)
 								{
 									$sDashboardDivId = $aExtraParams['dashboard_div_id'];
@@ -143,6 +145,7 @@ abstract class DashboardLayoutMultiCol extends DashboardLayout
 									}
 									$oDashlet->SetID($sDashletId);
 								}
+								$this->UpdateDashletsUserPrefs($oDashlet, $sDashletIdOrig, $aExtraParams);
 								$oDashlet->DoRender($oPage, $bEditMode, true /* bEnclosingDiv */, $aExtraParams);
 							}
 						}
@@ -175,6 +178,64 @@ abstract class DashboardLayoutMultiCol extends DashboardLayout
 		}
 		$oPage->add('</tbody></table>');
 	}
+
+	/**
+	 * Migrate dashlet specific prefs to new format
+	 *      Before 2.7.0 we were using the same for dashboard menu or dashboard attributes, standard or custom :
+	 *          <alias>-<class>|Dashlet<idx_dashlet>
+	 *      Since 2.7.0 it is the following, with a "CUSTOM_" prefix if necessary :
+	 *          * dashboard menu : <dashboard_id>_IDrow<row_idx>-col<col_idx>-<dashlet_idx>
+	 *          * dashboard attribute : <class>__<attcode>_IDrow<row_idx>-col<col_idx>-<dashlet_idx>
+	 *
+	 * @param \Dashlet $oDashlet
+	 * @param string $sDashletIdOrig
+	 *
+	 * @param array $aExtraParams
+	 *
+	 * @since 2.7.0 N°2735
+	 */
+	private function UpdateDashletsUserPrefs(\Dashlet $oDashlet, $sDashletIdOrig, array $aExtraParams)
+	{
+		$bIsDashletWithListPref = ($oDashlet instanceof  DashletObjectList);
+		if (!$bIsDashletWithListPref)
+		{
+			return;
+		}
+		/** @var \DashletObjectList $oDashlet */
+
+		$bDashletIdInNewFormat = ($sDashletIdOrig === $oDashlet->GetID());
+		if ($bDashletIdInNewFormat)
+		{
+			return;
+		}
+
+		$sNewPrefKey = $this->GetDashletAppUserPrefPrefix($oDashlet, $aExtraParams, $oDashlet->GetID());
+		$sPrefValueForNewKey = appUserPreferences::GetPref($sNewPrefKey, null);
+		$bHasPrefInNewFormat = ($sPrefValueForNewKey !== null);
+		if ($bHasPrefInNewFormat)
+		{
+			return;
+		}
+
+		$sOldPrefKey = $this->GetDashletAppUserPrefPrefix($oDashlet, $aExtraParams, $sDashletIdOrig);
+		$sPrefValueForOldKey = appUserPreferences::GetPref($sOldPrefKey, null);
+		$bHasPrefInOldFormat = ($sPrefValueForOldKey !== null);
+		if (!$bHasPrefInOldFormat)
+		{
+			return;
+		}
+
+		appUserPreferences::SetPref($sNewPrefKey, $sPrefValueForOldKey);
+		appUserPreferences::UnsetPref($sOldPrefKey);
+	}
+
+	private function GetDashletAppUserPrefPrefix(\DashletObjectList $oDashlet, array $aExtraParams, $sDashletId)
+	{
+		$sDataTableId = DashletObjectList::APPUSERPREFERENCE_TABLE_PREFIX.$sDashletId;
+		$oFilter = $oDashlet->GetDBSearch($aExtraParams);
+		$aClassAliases = $oFilter->GetSelectedClasses();
+		return DataTableSettings::GetAppUserPreferenceKey($aClassAliases, $sDataTableId);
+	}
 }
 
 class DashboardLayoutOneCol extends DashboardLayoutMultiCol
diff --git a/application/dashlet.class.inc.php b/application/dashlet.class.inc.php
index c62392860..8f0a4db90 100644
--- a/application/dashlet.class.inc.php
+++ b/application/dashlet.class.inc.php
@@ -892,6 +892,7 @@ class DashletPlainText extends Dashlet
 
 class DashletObjectList extends Dashlet
 {
+	const APPUSERPREFERENCE_TABLE_PREFIX = 'Dashlet';
 	/**
 	 * @inheritdoc
 	 */
@@ -913,7 +914,6 @@ class DashletObjectList extends Dashlet
 	public function Render($oPage, $bEditMode = false, $aExtraParams = array())
 	{
 		$sTitle = $this->aProperties['title'];
-		$sQuery = $this->aProperties['query'];
 		$sShowMenu = $this->aProperties['menu'] ? '1' : '0';
 
 		$oPage->add('<div class="dashlet-content">');
@@ -922,6 +922,20 @@ class DashletObjectList extends Dashlet
 		{
 			$oPage->add('<h1>'.$sHtmlTitle.'</h1>');
 		}
+		$oFilter = $this->GetDBSearch($aExtraParams);
+		$oBlock = new DisplayBlock($oFilter, 'list');
+		$aParams = array(
+			'menu' => $sShowMenu,
+			'table_id' => self::APPUSERPREFERENCE_TABLE_PREFIX.$this->sId,
+		);
+		$sBlockId = 'block_'.$this->sId.($bEditMode ? '_edit' : ''); // make a unique id (edition occurring in the same DOM)
+		$oBlock->Display($oPage, $sBlockId, array_merge($aExtraParams, $aParams));
+		$oPage->add('</div>');
+	}
+
+	public function GetDBSearch($aExtraParams = array())
+	{
+		$sQuery = $this->aProperties['query'];
 		if (isset($aExtraParams['query_params']))
 		{
 			$aQueryParams = $aExtraParams['query_params'];
@@ -935,15 +949,8 @@ class DashletObjectList extends Dashlet
 		{
 			$aQueryParams = array();
 		}
-		$oFilter = DBObjectSearch::FromOQL($sQuery, $aQueryParams);
-		$oBlock = new DisplayBlock($oFilter, 'list');
-		$aParams = array(
-			'menu' => $sShowMenu,
-			'table_id' => 'Dashlet'.$this->sId,
-		);
-		$sBlockId = 'block_'.$this->sId.($bEditMode ? '_edit' : ''); // make a unique id (edition occurring in the same DOM)
-		$oBlock->Display($oPage, $sBlockId, array_merge($aExtraParams, $aParams));
-		$oPage->add('</div>');
+
+		return DBObjectSearch::FromOQL($sQuery, $aQueryParams);
 	}
 
 	/**
diff --git a/application/datatable.class.inc.php b/application/datatable.class.inc.php
index a4662a27d..009937e88 100644
--- a/application/datatable.class.inc.php
+++ b/application/datatable.class.inc.php
@@ -1158,9 +1158,18 @@ class DataTableSettings implements Serializable
 	 */
 	protected function GetPrefsKey($sTableId = null)
 	{
-		if ($sTableId == null) $sTableId = '*';
+		return static::GetAppUserPreferenceKey($this->aClassAliases, $sTableId);
+	}
+
+	public static function GetAppUserPreferenceKey($aClassAliases, $sTableId)
+	{
+		if ($sTableId === null)
+		{
+			$sTableId = '*';
+		}
+
 		$aKeys = array();
-		foreach($this->aClassAliases as $sAlias => $sClass)
+		foreach($aClassAliases as $sAlias => $sClass)
 		{
 			$aKeys[] = $sAlias.'-'.$sClass;
 		}
diff --git a/application/user.preferences.class.inc.php b/application/user.preferences.class.inc.php
index 6febec34a..960384a3e 100644
--- a/application/user.preferences.class.inc.php
+++ b/application/user.preferences.class.inc.php
@@ -34,7 +34,7 @@ require_once(APPROOT.'/core/userrights.class.inc.php');
  */
 class appUserPreferences extends DBObject
 {
-	static $oUserPrefs = null; // Local cache
+	private static $oUserPrefs = null; // Local cache
 	
 	/**
 	 * Get the value of the given property/preference
@@ -43,7 +43,7 @@ class appUserPreferences extends DBObject
 	 * @param string $sDefaultValue The default value
 	 * @return string The value of the property for the current user
 	 */
-	static function GetPref($sCode, $sDefaultValue)
+	public static function GetPref($sCode, $sDefaultValue)
 	{
 		if (self::$oUserPrefs == null)
 		{
@@ -65,7 +65,7 @@ class appUserPreferences extends DBObject
 	 * @param string $sCode Code/Name of the property/preference to set
 	 * @param string $sValue Value to set
 	 */
-	static function SetPref($sCode, $sValue)
+	public static function SetPref($sCode, $sValue)
 	{
 		if (self::$oUserPrefs == null)
 		{
@@ -83,13 +83,13 @@ class appUserPreferences extends DBObject
 			self::Save();
 		}
 	}
-	
+
 	/**
 	 * Clears the value for a given preference (or list of preferences that matches a pattern), and updates the database
-	 * @param string $sPattern Code/Pattern of the properties/preferences to reset
+	 * @param string $sCodeOrPattern Code/Pattern of the properties/preferences to reset
 	 * @param boolean $bPattern Whether or not the supplied code is a PCRE pattern
 	 */
-	static function UnsetPref($sCodeOrPattern, $bPattern = false)
+	public static function UnsetPref($sCodeOrPattern, $bPattern = false)
 	{
 		if (self::$oUserPrefs == null)
 		{
@@ -124,7 +124,7 @@ class appUserPreferences extends DBObject
 	 * Call this function to get all the preferences for the user, packed as a JSON object
 	 * @return string JSON representation of the preferences
 	 */
-	static function GetAsJSON()
+	public static function GetAsJSON()
 	{
 		if (self::$oUserPrefs == null)
 		{
@@ -137,19 +137,19 @@ class appUserPreferences extends DBObject
 	/**
 	 * Call this function if the user has changed (like when doing a logoff...)
 	 */
-	static public function ResetPreferences()
+	public static function ResetPreferences()
 	{
 		self::$oUserPrefs = null;
 	}
 	/**
 	 * Call this function to ERASE all the preferences from the current user
 	 */
-	static public function ClearPreferences()
+	public static function ClearPreferences()
 	{
 		self::$oUserPrefs = null;
 	}
 	
-	static protected function Save()
+	protected static function Save()
 	{
 		if (self::$oUserPrefs != null)
 		{
@@ -166,7 +166,7 @@ class appUserPreferences extends DBObject
 	 * Loads the preferences for the current user, creating the record in the database
 	 * if needed
 	 */
-	static protected function Load()
+	protected static function Load()
 	{
 		if (self::$oUserPrefs != null) return;
 		$oSearch = new DBObjectSearch('appUserPreferences');