If you wish to gain full write access, click on ‘Advanced’, which can be found underneath the permissions box. To do this, from the View menu option, select Advanced Features.
Make sure all three groups, user group, admin group, and everyone group, have at least 'Read and Write' access Right-click the Windows folder and choose Properties. Quoting Tim Peters from import this, 'There should be one- and preferably only one -obvious way to do it. The following code example shows the use of the FileIOPermission(FileIOPermissionAccess, String) constructor to create a new instance of the FileIOPermission class with the write access to the C:\test. Note: SharePoint Designer is designed to request and use SharePoint permissions that grant the rights of managing and designing at the SharePoint site level. Under Group or user names, tap or click your name to see the permissions that you have.
