The comphelper::ConfigurationSet wrapper, used by the automatically generated
headers to access the configuration data from C++, is based on
com.sun.star.configuration.ReadOnlyAccess/ReadWriteAcess that provide an all-
locales view of the configuration data, i.e., a localized property is represented as a UNO object implementing various container interfaces (to access the per-locale values) instead of a plain value.

Hence,

  xLeaveAccess->getByName(C2U("Label")) >>= sLeafLabel;

silently changed its meaning, now silently failing to extract a string and
leaving sLeafLabel empty, which in turn causes the labels of extension option
pages to disappear from the "Tools - Options..." dialog.

This partially reverts commit 161c3f17 "Some
more comphelper/configurationhelper clean up."

Change-Id: I584c682ea6a7c8b9444b34f1867cc553ad160802