_force_colour->Bind (wxEVT_CHECKBOX, bind (&SubtitleAppearanceDialog::setup_sensitivity, this));
_force_effect_colour->Bind (wxEVT_CHECKBOX, bind (&SubtitleAppearanceDialog::setup_sensitivity, this));
_force_colour->Bind (wxEVT_CHECKBOX, bind (&SubtitleAppearanceDialog::setup_sensitivity, this));
_force_effect_colour->Bind (wxEVT_CHECKBOX, bind (&SubtitleAppearanceDialog::setup_sensitivity, this));