VCLXDevice, VCLXGraphics and derived class use a mutex that is really
a reference to the SolarMutex. They declare a function GetMutex() to
access tis reference to the SolarMutex, and the implementation
use
osl::SolarGuard aGuard(GetMutex())
to take a guad on the solar mutex.

This is confusing because some other class in that framework also implement
a GetMutex() function, but which this time return a regular Mutex.

Since this particular use of GetMutex() is to get the SolarMutex, and
invariably this is then used to take a Guard on the SolarMutex,
all these uses are replaced by a SolarMutexGuard object, which encapsulate
that behavior.