*** Please backup your registry, before making any changes ****
Close SQL Navigator
Start | Run | Regedit
Go to
HKEY_CURRENT_USER\Software\Quest Software\SQL Navigator 6.4.0\Confirmation
Confirm_Reopen_File_In_SameWindows - set to 0
Close the Registry Editor
Double-click on a file to open it. When you are prompted:
'File already open. Do you want to open the file in another tab?'
Check 'Don't ask me again' and click 'NO'