oapiSendMFDKey crash with ExternMFD

Consider the following code:

#define XSIZE 400
#define YSIZE 400

MFDSPEC spec = {{0,0,XSIZE,YSIZE},6,6,YSIZE/12,YSIZE/6};

Later, in clbkPreStep() of some module:

ExternMFD *mfd = new ExternMFD(spec);
oapiSendMFDKey(mfd->Id(), OAPI_KEY_F1);

This code crashes with segmentation violation in oapiSendMFDKey.

According to documentation, ExternMFD::Id() returns object's this pointer cast to UINT. On the other hand, built-in MFDs have IDs equal to 0, 1, ... and so on. Thus, it appears that oapiSendMFDKey incorrectly dereferences MFD IDs issued by ExternMFD.