BCGControlBar Pro for MFC
void CBCGPCaptionBar::EnableButton ( BOOL  bEnable = TRUE)

Enables or disables a button, which has been placed on the caption bar.

Call this member function to enable or disable button that has been set by calling the SetButton() function. If the button is disabled it is not grayed and retains the "flat" style.

bEnableTRUE - enables the button, FALSE - disables the button.