BCGControlBar Pro for MFC
virtual BOOL CBCGPToolbarButton::CanBeStretched ( ) const
inlinevirtual

Indicates whether a button can be stretched in customization mode.

Returns
Nonzero if a button can be stretched, otherwise 0.

Button can be stretched in customization mode. Usually, you need to return TRUE in case of the variable-width controls such as combo box or slider.