HTTP Enforcer and the RealURL extension:ref:

Since 1.0.8, HTTPS Enforcer supports the mapping of a page hierarchy and GETvars to directories as done by the RealURL extension (with class.tx_realurl_advanced.php).

To avoid alerts that “parts of this page are loaded over an insecure connection ” when redirected to an encrypted page by HTTP Enforcer, you have to make realurl's config.baseURL depend on the state of HTTP Enforcer. One way to do this in conjunction with the page header field is to add the following lines to you site template's Setup:

[globalVar = TSFE:page|tx_httpsenforcer_force_secure = 0]
  config.baseURL = http://www.mydomain.org/
[else]
  config.baseURL = https://ssl.mydomain.org/
[global]

If you are using the plugin.tx_httpsenforcer.require_ssl constant, I suggest you set config.baseURL accordingly in the same template record.