refactor _grabbed into cairo_widget

gtk2_ardour/ardour_knob.cc

@@ -56,7 +56,6 @@ ArdourKnob::Element ArdourKnob::default_elements = ArdourKnob::Element (ArdourKn
 ArdourKnob::ArdourKnob (Element e)
 	: _elements (e)
 	, _hovering (false)
-	, _grabbed (false)
 {
 	ARDOUR_UI_UTILS::ColorsChanged.connect (sigc::mem_fun (*this, &ArdourKnob::color_handler));
 }

gtk2_ardour/ardour_knob.h

@@ -84,7 +84,6 @@ public:
 	BindingProxy                binding_proxy;
 
 	bool _hovering;
-	bool _grabbed;
 	float _grabbed_y;
 
 	float _val;  //percent of knob travel

libs/gtkmm2ext/cairo_widget.cc

@@ -28,6 +28,7 @@ CairoWidget::CairoWidget ()
 	: _active_state (Gtkmm2ext::Off)
 	, _visual_state (Gtkmm2ext::NoVisualState)
 	, _need_bg (true)
+	, _grabbed (false)
 	, _name_proxy (this, X_("name"))
 {
 	_name_proxy.connect (sigc::mem_fun (*this, &CairoWidget::on_name_changed));

libs/gtkmm2ext/gtkmm2ext/cairo_widget.h

@@ -85,6 +85,8 @@ protected:
 	Gtkmm2ext::ActiveState _active_state;
 	Gtkmm2ext::VisualState _visual_state;
 	bool                   _need_bg;
+	
+	bool		_grabbed;
 
   private:
 	Glib::SignalProxyProperty _name_proxy;