BCGControlBar Pro for MFC
BOOL CBCGPToolbarButton::IsLocked ( ) const

Returns a flag indicating whether a button belongs to the locked (non-customizable) toolbar and can't be customized (dragged, dropped or edited).

Nonzero if a button is locked; otherwise 0.

When you load a toolbar using CBCGPToolBar::LoadToolBar, you specify the bLocked flag. The toolbar object stores this flag and passes it to the constructor of toolbar buttons (CBCGPToolbarButton) when the buttons are inserted into this toolbar.