BCGControlBar Pro for MFC
void CBCGPMDIFrameWnd::MDITabMoveToNextGroup ( BOOL  bNext = TRUE)

Moves the active tab to the next or previous group.

Use this function to move an active tab from the currently active tabbed window to the previous or next tabbed window.

bNextIf TRUE - move to the next window. If FALSE - move to the previous window.