diff --git a/include/nana/gui/widgets/tabbar.hpp b/include/nana/gui/widgets/tabbar.hpp
index 02722d96..a788dc29 100644
--- a/include/nana/gui/widgets/tabbar.hpp
+++ b/include/nana/gui/widgets/tabbar.hpp
@@ -337,8 +337,6 @@ namespace nana
 
 namespace nana
 {
-	namespace ng
-	{
 		namespace drawerbase
 		{
 			namespace tabbar_lite
@@ -352,7 +350,7 @@ namespace nana
 					driver();
 					~driver();
 
-					model* get_model();
+					model* get_model() const throw();
 				private:
 					//Overrides drawer_trigger's method
 					void attached(widget_reference, graph_reference)	override;
@@ -373,11 +371,15 @@ namespace nana
 			tabbar_lite() = default;
 			tabbar_lite(window, bool visible = true, const::nana::rectangle& = {});
 
+		public: //capacity
+			std::size_t length() const;
+
+		public: //modifiers
+			void attach(std::size_t pos, window);
 
 			void push_back(std::string text, ::nana::any par = {});
 			void push_front(std::string text, ::nana::any par = {});
 		};
-	}
 }
 
 #endif
diff --git a/source/gui/place.cpp b/source/gui/place.cpp
index aa1f02f8..92033b99 100644
--- a/source/gui/place.cpp
+++ b/source/gui/place.cpp
@@ -1602,16 +1602,83 @@ namespace nana
 		}
 	private:
 		//Implement dock_notifier_interface
+		/*
+		static div_dockpane* _m_left(div_dockpane* dockpn)
+		{
+			for (auto & dv : dockpn->div_owner->children)
+			{
+				if (dv->div_next == dockpn)
+					return static_cast<div_dockpane*>(dv.get());
+			}
+			return nullptr;
+		}
+
+		::nana::size _m_calc_space_if_remove(div_dockpane* dockpn)
+		{
+			div_owner->field_area;
+
+			auto left = _m_left(dockpn);
+			while (left && !left->display)
+				left = _m_left(left);
+
+			auto right = dockpn->div_next;
+			while (right && !right->display)
+				right = right->div_next;
+
+		}
+		*/
 		void notify_float() override
 		{
 			set_display(false);
 
+			/*
+			this->width_percent = field_area.width / div_owner->field_area.width * 100.0;
+			this->height_percent = field_area.height / div_owner->field_area.height * 100.0;
+
+
+			//Re-layout the siblings
+			double other_px = this->div_owner->field_area.height - this->field_area.height;
+			for (auto& div : this->div_owner->children)
+			{
+				if (!div->display)
+					continue;
+
+				//deprecated
+				//auto wgt_percent = div->field_area.height / other_px;
+				//div->weight.assign_percent(wgt_percent * 100.0);
+
+				//???? other_px issue, have
+				auto dockpn = dynamic_cast<div_dockpane*>(div.get());
+				dockpn->width_percent = div->field_area.width / other_px * 100.0;
+				dockpn->height_percent = div->field_area.height / other_px * 100.0;
+			}
+
+			this->weight.assign_percent((double(field_area.height) / this->div_owner->field_area.height) * 100.0);
+			*/
 			impl_ptr_->collocate();
 		}
 
 		void notify_dock() override
 		{
 			indicator_.docker.reset();
+
+			/*
+			//Re-layout the siblings
+			auto px = this->weight.get_value(div_owner->field_area.height);
+
+			double other_px = this->div_owner->field_area.height - px;
+
+			this->weight.assign_percent(px / div_owner->field_area.height * 100);
+			for (auto& div : this->div_owner->children)
+			{
+				if (!div->display)
+					continue;
+
+				auto px = div->weight.get_value(static_cast<int>(other_px));
+				div->weight.assign_percent(px / div_owner->field_area.height * 100);
+			}
+			*/
+
 			set_display(true);
 			impl_ptr_->collocate();
 		}
@@ -1744,6 +1811,8 @@ namespace nana
 		}
 	public:
 		field_dock * dockable_field{ nullptr };
+		double	width_percent{ -1 };	//[-1, 100] it's invalid if it is less than zero
+		double	height_percent{ -1 };	//[-1, 100]
 	private:
 		implement * impl_ptr_;
 		bool created_{ false };
@@ -1751,7 +1820,7 @@ namespace nana
 		struct indicator_tag
 		{
 			paint::graphics graph;
-			//panel<true> widget;
+			//panel<true> widget;	//deprecated
 			rectangle	r;
 			std::unique_ptr<panel<true>> dock_area;
 			std::unique_ptr<form> docker;
@@ -1766,6 +1835,19 @@ namespace nana
 			:	division(kind::dock, std::move(name))
 		{}
 
+		division* front() const
+		{
+			auto i = children.cbegin();
+			
+			for (auto i = children.cbegin(); i != children.cend(); ++i)
+			{
+				if (i->get()->display)
+					return i->get();
+			}
+
+			return nullptr;
+		}
+
 		void collocate(window wd) override
 		{
 			auto area = this->margin_area();
@@ -1773,20 +1855,30 @@ namespace nana
 			unsigned vert_count = 0, horz_count = 0;
 			unsigned vert_weight = 0, horz_weight = 0;
 
-			bool prev_attr = _m_is_vert(children.front()->dir);
+			bool prev_attr = _m_is_vert(front()->dir);
 			(prev_attr ? horz_count : vert_count) = 1;
 
 			for (auto & child : children)
 			{
-				auto is_vert = _m_is_vert(child->dir);
+				if (!child->display)
+					continue;
 
-				if (child->weight.is_not_none())
+				auto child_dv = dynamic_cast<div_dockpane*>(child.get());
+
+				const auto is_vert = _m_is_vert(child->dir);
+
+				/*
+				if (is_vert)
 				{
-					if (is_vert)
-						vert_weight += static_cast<unsigned>(child->weight.get_value(area.height));
-					else
-						horz_weight += static_cast<unsigned>(child->weight.get_value(area.width));
+					if (child_dv->height_percent >= 0)
+						vert_weight += static_cast<unsigned>(child_dv->height_percent * area.height);
 				}
+				else
+				{
+					if (child_dv->width_percent >= 0)
+						horz_weight += static_cast<unsigned>(child_dv->width_percent * area.width);
+				}
+				*/
 
 				if (is_vert == prev_attr)
 				{
@@ -1819,12 +1911,36 @@ namespace nana
 
 			for (auto & child : children)
 			{
+				if (!child->display)
+					continue;
+
+				auto child_dv = dynamic_cast<div_dockpane*>(child.get());
 				double weight;
+
+				/*	//deprecated
 				if (child->weight.is_not_none())
 					weight = child->weight.get_value(_m_is_vert(child->dir) ? area.height : area.height);
 				else
 					weight = (_m_is_vert(child->dir) ? auto_vert_w : auto_horz_w);
 
+				if (_m_is_vert(child->dir))
+				{
+					if (child_dv->height_percent >= 0)
+						weight = child_dv->height_percent * area.height;
+					else
+						weight = auto_vert_w;
+				}
+				else
+				{
+					if (child_dv->width_percent >= 0)
+						weight = child_dv->width_percent * area.width;
+					else
+						weight = auto_horz_w;
+				}
+				*/
+
+				weight = (_m_is_vert(child->dir) ? auto_vert_w : auto_horz_w);
+
 				::nana::rectangle child_r;
 				switch (child->dir)
 				{
@@ -2216,7 +2332,12 @@ namespace nana
 				std::vector<std::unique_ptr<division>> adjusted_children;
 				for (auto & child : children)
 				{
-					adjusted_children.emplace_back(new div_dockpane(std::move(child->name), this, child->dir));
+					//ignores weight if it is a dockpane
+					//internally, width_percent/height_percent are employed for weight
+					auto dockpn = new div_dockpane(std::move(child->name), this, child->dir);
+					dockpn->div_next = child->div_next;
+					dockpn->div_owner = child->div_owner;
+					adjusted_children.emplace_back(dockpn);
 				}
 
 				children.swap(adjusted_children);
diff --git a/source/gui/place_parts.hpp b/source/gui/place_parts.hpp
index 3a1b670e..b90732f5 100644
--- a/source/gui/place_parts.hpp
+++ b/source/gui/place_parts.hpp
@@ -198,7 +198,7 @@ namespace nana
 				});
 
 				if (panels_.size() > 1)
-					tabbar_.reset(new tabbar<int>(*this));
+					tabbar_.reset(new tabbar_lite(*this));
 
 				std::size_t pos = 0;
 				for (auto & pn : panels_)
@@ -208,8 +208,10 @@ namespace nana
 						pn.widget_ptr = pn.factory_fn(*this);
 						if (tabbar_)
 						{
-							tabbar_->push_back(pn.widget_ptr->caption());
-							tabbar_->relate(pos++, pn.widget_ptr->handle());
+							tabbar_->push_back(::nana::charset(pn.widget_ptr->caption()));
+							tabbar_->attach(pos++, pn.widget_ptr->handle());
+							//tabbar_->push_back(pn.widget_ptr->caption());
+							//tabbar_->relate(pos++, pn.widget_ptr->handle());
 						}
 					}
 				}
@@ -262,7 +264,7 @@ namespace nana
 			std::unique_ptr<form>	container_;
 			dockarea_caption	caption_;
 			std::deque<panel>	panels_;
-			std::unique_ptr<tabbar<int>> tabbar_;
+			std::unique_ptr<tabbar_lite> tabbar_;
 
 			struct moves
 			{
diff --git a/source/gui/widgets/tabbar.cpp b/source/gui/widgets/tabbar.cpp
index 624b5db1..3796a1ac 100644
--- a/source/gui/widgets/tabbar.cpp
+++ b/source/gui/widgets/tabbar.cpp
@@ -1275,8 +1275,6 @@ namespace nana
 #include <forward_list>
 namespace nana
 {
-	namespace ng
-	{
 		namespace drawerbase
 		{
 			namespace tabbar_lite
@@ -1286,6 +1284,7 @@ namespace nana
 					::std::string text;
 					::nana::any	value;
 					::std::pair<int, int> pos_ends;
+					::nana::window attached_window{ nullptr };
 
 					item(std::string t, ::nana::any v)
 						: text(std::move(t)), value(std::move(v))
@@ -1361,6 +1360,23 @@ namespace nana
 						return items_;
 					}
 
+					void show_attached_window()
+					{
+						if (indexes_.active_pos != npos)
+						{
+							auto i = items_.cbegin();
+							std::advance(i, indexes_.active_pos);
+							API::show_window(i->attached_window, true);
+
+							std::size_t pos = 0;
+							for (auto & m : items_)
+							{
+								if (pos++ != indexes_.active_pos)
+									API::show_window(m.attached_window, false);
+							}
+						}
+					}
+
 					bool track_pointer(const point& pos)
 					{
 						std::size_t item_pos = 0;
@@ -1476,7 +1492,7 @@ namespace nana
 						delete model_;
 					}
 
-					model* driver::get_model()
+					model* driver::get_model() const throw()
 					{
 						return model_;
 					}
@@ -1514,10 +1530,12 @@ namespace nana
 					void driver::mouse_down(graph_reference graph, const arg_mouse&)
 					{
 						auto & indexes = model_->get_indexes();
-						if (indexes.hovered_pos == model_->npos)
+						if ((indexes.hovered_pos == model_->npos) || (indexes.active_pos == indexes.hovered_pos))
 							return;
 
 						indexes.active_pos = indexes.hovered_pos;
+						model_->show_attached_window();
+
 						refresh(graph);
 						API::lazy_refresh();
 					}
@@ -1532,6 +1550,41 @@ namespace nana
 			this->create(parent_wd, r, visible);
 		}
 
+		//capacity
+		std::size_t tabbar_lite::length() const
+		{
+			auto& items = get_drawer_trigger().get_model()->items();
+			internal_scope_guard lock;
+
+			std::size_t off = 0;
+			auto i = items.cbegin(), end = items.cend();
+			while (i != end)
+			{
+				++i;
+				++off;
+			}
+			return off;
+		}
+
+		//modifiers
+		void tabbar_lite::attach(std::size_t pos_set, window wd)
+		{
+			auto model = get_drawer_trigger().get_model();
+			internal_scope_guard lock;
+
+			for (auto & m : model->items())
+			{
+				if (0 == pos_set--)
+				{
+					m.attached_window = wd;
+					model->show_attached_window();
+					return;
+				}
+			}
+
+			throw std::out_of_range("invalid position of tabbar_lite");
+		}
+
 		void tabbar_lite::push_back(std::string text, ::nana::any any)
 		{
 			auto & items = get_drawer_trigger().get_model()->items();
@@ -1561,5 +1614,4 @@ namespace nana
 			API::refresh_window(handle());
 		}
 		//end class tabbar
-	}
 }//end namespace nana