If you use variable completion to replace an existing variable that is within other characters then after the replacement the other characters are still intact as expected, e.g:  
  
 1) Text has: “%FBPROJECTDIR%\Test” 
 2) Put cursor inside the text and from variable completion select say FBDIR and the result is “%FBDIR%\Test”. 
  
 However if you want to insert a new variable then the remaining text is lost, e.g.: 
  
 1) Text has: “\Test” after removing a hard coded path. 
 2) Put cursor after first quote and from the variable completion select variable and the remainder of the line is removed leaving: 
  
 "%FBDIR% 
  
 The only workaround is to ensure there is a space after the cursor location, which incidentally gets removed after the variable completion.  
  
 FB5 worked correctly in both cases.  Using FB 6.3.0.1666 
Hi Simon, 
  
 We’ve checked a fix in for this issue, will let you know as soon as a new build is available. 
  
 Regards, 
 Paul.