Code folding (#pragma region) in Qt creator

Currently not.

I think it is better to structure your code by using code anyways. The regions as also found in C# are imho a bad substitute for proper structuring and keeping things maintainable.

I think you can do this:

Reformat your someclass.cpp

namespace ns
{
  CClass::CClass() {}
  CClass::~CClass() {}
  void CClass::Test() {}
  void CClass::Test2() {}
  void CClass::Test3() {}
}

for example as

namespace ns // construction-destruction
{
  CClass::CClass() {}
  CClass::~CClass() {}
}
namespace ns // test-region
{
  void CClass::Test() {}
  void CClass::Test2() {}
  void CClass::Test3() {}
}