src/2D.cpp
void TwoDActivate ()
{
    // Register the actual drawing func.
    // This actually is a deprecated call, but it is at the same time the recommended way to draw labels,
    // see https://developer.x-plane.com/code-sample/coachmarks/
    XPLMRegisterDrawCallback(CPLabelDrawing,
                             xplm_Phase_Window,
                             1,                        // after
                             nullptr);
}
/// Activate actual label drawing, esp. set up drawing callback
Activate actual label drawing, esp. set up drawing callback
Activate actual label drawing esp . set up drawing callback
void TwoDActivate ()
{
    XPLMRegisterDrawCallback(CPLabelDrawing,
                             xplm_Phase_Window,
                             1,                        
                             nullptr);
}
void TwoDActivate ( ) { XPLMRegisterDrawCallback ( CPLabelDrawing , xplm_Phase_Window , 1 , nullptr ) ; }
Activate actual label drawing, esp.
Activate actual label drawing esp .
// Register the actual drawing func. // This actually is a deprecated call, but it is at the same time the recommended way to draw labels, // see https://developer.x-plane.com/code-sample/coachmarks/ // after