Placing vtkCaptionActor2D in 3D space

Hi , I’ve been messing around with the vtkCaptionActor2D, and wrote an interaction style for it by following this example : such that one can hold down on it and place it’s caption position on mouse click and drag.

However , if I attempt to rotate the camera to look towards either the X or Y coordinate in world space, the vtkCaptionActor2D seems to only accept mouse event positions in one direction only: Here’s the block of code that handles the resolution of it’s position:

virtual void OnLeftButtonUp() override

     hold = false; //flag to check if the left mouse button is held down

     if(LastPickedActor!=NULL && move)
     {   //Unhighlight actor

         //Get Mouse position
         int* position = this->GetInteractor()->GetEventPosition();
         int x = position[0];
         int y = position[1];

         //Set coordinate system to display system
         vtkSmartPointer<vtkCoordinate> coordinate = vtkSmartPointer<vtkCoordinate>::New();
         coordinate->SetValue(x,y,0); //Set Screen coordinates
         //Compute world coordinates from screen display coordinates
        double* worldCoordinates = coordinate->GetComputedWorldValue(render->GetRenderWindow()->GetRenderers()->GetFirstRenderer());
        double worldX{worldCoordinates[0]};
        double worldY{worldCoordinates[1]};
        double worldZ{worldCoordinates[2]};


        //flag to check whether mouse is moving or not
         move = false;


Is there something I am missing to transform it’s position to world space or does Actor 2D only work with an x-y plane ?