diff --git a/LICENSE_1_0.txt b/LICENSE
similarity index 100%
rename from LICENSE_1_0.txt
rename to LICENSE
diff --git a/include/nana/gui/widgets/treebox.hpp b/include/nana/gui/widgets/treebox.hpp
index ae5e03b1..9901e1bf 100644
--- a/include/nana/gui/widgets/treebox.hpp
+++ b/include/nana/gui/widgets/treebox.hpp
@@ -421,6 +421,9 @@ namespace nana
 		
 		bool checkable() const; ///< Determinte whether the checkboxs are enabled.
 
+		/// Clears the contents
+		void clear();
+
         /// \brief Creates an icon scheme with the specified name.
         ///
         /// The icon scheme includes 3 images for node states. 
diff --git a/source/gui/widgets/treebox.cpp b/source/gui/widgets/treebox.cpp
index c75aea52..76f6dc20 100644
--- a/source/gui/widgets/treebox.cpp
+++ b/source/gui/widgets/treebox.cpp
@@ -866,8 +866,7 @@ namespace nana
 				item_proxy& item_proxy::check(bool ck)
 				{
 					trigger_->check(node_, ck ? checkstate::checked : checkstate::unchecked);
-					if(trigger_->draw())
-						API::update_window(trigger_->impl()->data.widget_ptr->handle());
+					trigger_->draw();
 					return *this;
 				}
 
@@ -1664,7 +1663,8 @@ namespace nana
 					if (!impl_->attr.auto_draw)
 						return false;
 
-					impl_->draw(false);
+					if(impl_->draw(false))
+						API::update_window(impl_->data.widget_ptr->handle());
 					return true;
 				}
 
@@ -2198,6 +2198,13 @@ namespace nana
 			return get_drawer_trigger().checkable();
 		}
 
+		void treebox::clear()
+		{
+			auto impl = get_drawer_trigger().impl();
+			impl->attr.tree_cont.clear();
+			get_drawer_trigger().draw();
+		}
+
 		treebox::node_image_type& treebox::icon(const std::string& id) const
 		{
 			return get_drawer_trigger().icon(id);
diff --git a/source/paint/graphics.cpp b/source/paint/graphics.cpp
index 2114d69a..201d18a8 100644
--- a/source/paint/graphics.cpp
+++ b/source/paint/graphics.cpp
@@ -777,12 +777,22 @@ namespace paint
 					::ReleaseDC(reinterpret_cast<HWND>(dst), dc);
 				}
 #elif defined(NANA_X11)
-				Display * display = nana::detail::platform_spec::instance().open_display();
+				auto & spec = nana::detail::platform_spec::instance();
+				
+				Display * display = spec.open_display();
+				
+				nana::detail::platform_scope_guard lock;
+				
 				::XCopyArea(display,
 					impl_->handle->pixmap, reinterpret_cast<Window>(dst), impl_->handle->context,
 						sx, sy, width, height, dx, dy);
 
-				::XMapWindow(display, reinterpret_cast<Window>(dst));
+				XWindowAttributes attr;
+				spec.set_error_handler();
+				::XGetWindowAttributes(display, reinterpret_cast<Window>(dst), &attr);
+				if(BadWindow != spec.rev_error_handler() && attr.map_state != IsUnmapped)
+					::XMapWindow(display, reinterpret_cast<Window>(dst));
+					
 				::XFlush(display);
 #endif
 			}