DECLARE_FRAME_WND_CLASS_EX(GetWndClassName(), IDR_QUEUE, 0, COLOR_3DFACE);
this line looks very similar to
QueueFrame.h
DECLARE_FRAME_WND_CLASS_EX(_T("QueueFrame"), IDR_QUEUE, 0, COLOR_3DFACE);
While this looks like a copy paste oversight, (the dual usage of IDR_QUEUE), it maybe intentional. I just thought that FlatTabCtrl should have it's own IDR control.