diff --git a/phpgwapi/inc/class.groupdav_principals.inc.php b/phpgwapi/inc/class.groupdav_principals.inc.php
index 4f9c334e1c..a28fde9f1b 100644
--- a/phpgwapi/inc/class.groupdav_principals.inc.php
+++ b/phpgwapi/inc/class.groupdav_principals.inc.php
@@ -1161,30 +1161,9 @@ class groupdav_principals extends groupdav_handler
 		$displayname = translation::convert($resource['name'],	translation::charset(), 'utf-8');
 
 		return ($is_location ? 'locations/' : 'resources/').$resource['res_id'].'-'.
-			preg_replace('/[^a-z0-9]+/i','-', self::to_ascii($resource['name']));
+			preg_replace('/[^a-z0-9]+/i','-', translation::to_ascii($resource['name']));
 	}
 
-	/**
-	 * Transliterate utf-8 filename to ascii, eg. 'Äpfel' --> 'Aepfel'
-	 *
-	 * @param string $str
-	 * @return string
-	 */
-	protected static function to_ascii($str)
-	{
-		static $extra = array(
-			'ß' => 'ss',
-		);
-		$str = htmlentities($str,ENT_QUOTES,translation::charset());
-		$str = str_replace(array_keys($extra),array_values($extra),$str);
-		$str = preg_replace('/&([aAuUoO])uml;/','\\1e',$str);	// replace german umlauts with the letter plus one 'e'
-		$str = preg_replace('/&([a-zA-Z])(grave|acute|circ|ring|cedil|tilde|slash|uml);/','\\1',$str);	// remove all types of accents
-		$str = preg_replace('/&([a-zA-Z]+|#[0-9]+|);/','',$str);	// remove all other entities
-
-		return $str;
-	}
-
-
 	/**
 	 * Check if resource is a location
 	 *
diff --git a/phpgwapi/inc/class.html.inc.php b/phpgwapi/inc/class.html.inc.php
index 507eff95a6..33eb4d3918 100644
--- a/phpgwapi/inc/class.html.inc.php
+++ b/phpgwapi/inc/class.html.inc.php
@@ -1055,7 +1055,7 @@ class html
 	{
 		if (!is_array($options)) $options = explode(',',$options);
 		if (!is_array($names))   $names   = explode(',',$names);
-
+		//if (empty($options)) return "";//this should not be needed
 		foreach($options as $n => $val)
 		{
 			if ($val != '' && $names[$n] != '')
@@ -1368,8 +1368,9 @@ class html
 	 * @param string $mime='' mimetype or '' (default) to detect it from filename, using mime_magic::filename2mime()
 	 * @param int $length=0 content length, default 0 = skip that header
 	 * @param boolean $nocache=true send headers to disallow browser/proxies to cache the download
+	 * @param boolean $forceDownload=true send headers to handle as attachment/download
 	 */
-	public static function content_header($fn,$mime='',$length=0,$nocache=True)
+	public static function content_header($fn,$mime='',$length=0,$nocache=True,$forceDownload=true)
 	{
 		// if no mime-type is given or it's the default binary-type, guess it from the extension
 		if(empty($mime) || $mime == 'application/octet-stream')
@@ -1378,18 +1379,22 @@ class html
 		}
 		if($fn)
 		{
+			if ($forceDownload===true)
+			{
+				$attachment = ' attachment;';
+			}
+			else
+			{
+				$attachment = ' inline;';
+			}
 			// limit IE hack (no attachment in Content-disposition header) to IE < 9
 			if(self::$user_agent == 'msie' && self::$ua_version < 9)
 			{
 				$attachment = '';
 			}
-			else
-			{
-				$attachment = ' attachment;';
-			}
 
 			// Show this for all
-			header('Content-disposition:'.$attachment.' filename="'.$fn.'"');
+			self::content_disposition_header($fn,$forceDownload);
 			header('Content-type: '.$mime);
 
 			if($length)
@@ -1407,6 +1412,31 @@ class html
 		}
 	}
 
+	/**
+	 * Output content-disposition header for file downloads
+	 *
+	 * @param string $fn filename
+	 * @param boolean $forceDownload=true send headers to handle as attachment/download
+	 */
+	public static function content_disposition_header($fn,$forceDownload=true)
+	{
+			if ($forceDownload===true)
+			{
+				$attachment = ' attachment;';
+			}
+			else
+			{
+				$attachment = ' inline;';
+			}
+			// limit IE hack (no attachment in Content-disposition header) to IE < 9
+			if(self::$user_agent == 'msie' && self::$ua_version < 9)
+			{
+				$attachment = '';
+			}
+
+			header('Content-disposition:'.$attachment.' filename="'.translation::to_ascii($fn).'"; filename*=utf-8\'\''.rawurlencode($fn));
+	}
+
 	/**
 	 * split html by PRE tag, return array with all content pre-sections isolated in array elements
 	 * @author Leithoff, Klaus
diff --git a/phpgwapi/inc/class.translation.inc.php b/phpgwapi/inc/class.translation.inc.php
index 3f43fcc1f7..a834e08fae 100644
--- a/phpgwapi/inc/class.translation.inc.php
+++ b/phpgwapi/inc/class.translation.inc.php
@@ -624,6 +624,26 @@ class translation
 		return $charsets;
 	}
 
+	/**
+	 * Transliterate utf-8 filename to ascii, eg. 'Äpfel' --> 'Aepfel'
+	 *
+	 * @param string $str
+	 * @return string
+	 */
+	static function to_ascii($str)
+	{
+		static $extra = array(
+			'&szlig;' => 'ss',
+		);
+		$str = htmlentities($str,ENT_QUOTES,self::charset());
+		$str = str_replace(array_keys($extra),array_values($extra),$str);
+		$str = preg_replace('/&([aAuUoO])uml;/','\\1e',$str);	// replace german umlauts with the letter plus one 'e'
+		$str = preg_replace('/&([a-zA-Z])(grave|acute|circ|ring|cedil|tilde|slash|uml);/','\\1',$str);	// remove all types of accents
+		$str = preg_replace('/&([a-zA-Z]+|#[0-9]+|);/','',$str);	// remove all other entities
+
+		return $str;
+	}
+
 	/**
 	 * converts a string $data from charset $from to charset $to
 	 *
diff --git a/phpgwapi/inc/class.vfs_webdav_server.inc.php b/phpgwapi/inc/class.vfs_webdav_server.inc.php
index db8bf5d925..307cdfd376 100644
--- a/phpgwapi/inc/class.vfs_webdav_server.inc.php
+++ b/phpgwapi/inc/class.vfs_webdav_server.inc.php
@@ -692,7 +692,7 @@ class vfs_webdav_server extends HTTP_WebDAV_Server_Filesystem
 			}
 			if ($this->force_download)
 			{
-				header('Content-disposition: attachment; filename="'.egw_vfs::basename($options['path']).'"');
+				html::content_disposition_header(egw_vfs::basename($options['path']),true);
 			}
 		}
 		return $ok;
@@ -923,4 +923,4 @@ class vfs_webdav_server extends HTTP_WebDAV_Server_Filesystem
 		}
 		return parent::PUT($options);
 	}
-}
\ No newline at end of file
+}