This method has been introduced because the control doesn't send the MouseMove event when the user exits the button area with the button still pressed.
When calling this method with the bCapture parameter set to TRUE, the MouseMove event will still fire when the mouse exits the button area. Note however that it must be called for every button You have on Your form or dialog.
By default the mouse capture is disabled.
control.MouseCapture (bCapture as boolean)
void control.MouseCapture (BOOL bCapture);