diff --git a/include/nana/basic_types.hpp b/include/nana/basic_types.hpp
index b190ea42..a041279b 100644
--- a/include/nana/basic_types.hpp
+++ b/include/nana/basic_types.hpp
@@ -312,7 +312,14 @@ namespace nana
 		/// @param lightness  in range of [0, 1]
 		color& from_hsl(double hue, double saturation, double lightness);	///< immutable alpha channel
 
-		color blend(const color& blending_color, double alpha) const;
+		/// Blends color
+		/**
+		 * Returns a color which is blended as this * (1 - fade_rate) + blending_color * fade_rate
+		 * @param blending_color Color to blend
+		 * @param fade_rate Blending rate for blending_color
+		 * @return a blended color
+		 */
+		color blend(const color& blending_color, double fade_rate) const;
 
 		/// Determines whether the color is completely transparent.
 		bool invisible() const;
diff --git a/source/gui/detail/window_manager.cpp b/source/gui/detail/window_manager.cpp
index e948aeec..476b657b 100644
--- a/source/gui/detail/window_manager.cpp
+++ b/source/gui/detail/window_manager.cpp
@@ -219,8 +219,6 @@ namespace detail
 			Key first;
 			Value second;
 
-			key_value_rep() = default;
-
 			key_value_rep(const Key& k)
 				: first(k), second{}
 			{
@@ -258,15 +256,7 @@ namespace detail
 		std::vector<key_value_rep> table_;
 	};
 
-	//class window_manager
-			struct window_handle_deleter
-			{
-				void operator()(basic_window* wd) const
-				{
-					delete wd;
-				}
-			};
-			
+	//class window_manager			
 			//struct wdm_private_impl
 			struct window_manager::wdm_private_impl
 			{
@@ -506,7 +496,7 @@ namespace detail
 				if (impl_->wd_register.available(owner))
 				{
 					if (owner->flags.destroying)
-						throw std::runtime_error("the specified owner is destory");
+						throw std::runtime_error("the specified owner is destoryed");
 
 #ifndef WIDGET_FRAME_DEPRECATED
 					native = (category::flags::frame == owner->other.category ?
diff --git a/source/gui/widgets/listbox.cpp b/source/gui/widgets/listbox.cpp
index c49841c5..21a5f5f6 100644
--- a/source/gui/widgets/listbox.cpp
+++ b/source/gui/widgets/listbox.cpp
@@ -4166,16 +4166,16 @@ namespace nana
 								{
 									if (item_ptr->flags.selected != sel)
 									{
-										item_ptr->flags.selected = sel;
-										lister.emit_cs(abs_item_pos, true);
-
-										if (item_ptr->flags.selected)
+										if (sel)
 										{
 											lister.cancel_others_if_single_enabled(true, abs_item_pos);
 											essence_->lister.latest_selected_abs = abs_item_pos;
 										}
 										else if (essence_->lister.latest_selected_abs == abs_item_pos)
 											essence_->lister.latest_selected_abs.set_both(npos);
+
+										item_ptr->flags.selected = sel;
+										lister.emit_cs(abs_item_pos, true);
 									}
 								}
 								else
diff --git a/source/paint/graphics.cpp b/source/paint/graphics.cpp
index f31f3afd..62f74016 100644
--- a/source/paint/graphics.cpp
+++ b/source/paint/graphics.cpp
@@ -271,7 +271,7 @@ namespace paint
 
 		graphics::operator bool() const noexcept
 		{
-			return impl_->handle;
+			return (impl_->handle != nullptr);
 		}
 
 		drawable_type graphics::handle() const