diff --git a/component/component.ts b/component/component.ts
index 80eb5e0..f2c199d 100644
--- a/component/component.ts
+++ b/component/component.ts
@@ -47,7 +47,7 @@ namespace $ {
 
 		@ $mol_mem
 		prop_names() {
-			return this.$.$mol_view_tree2_class_props( this.tree() ).map( tree => this.$.$mol_view_tree2_prop_split( tree ).name.text() )
+			return this.$.$mol_view_tree2_class_props( this.tree() ).map( tree => this.$.$mol_view_tree2_prop_parts( tree ).name )
 		}
 
 		@ $mol_mem
diff --git a/studio.view.ts b/studio.view.ts
index 99a3300..b1d3278 100644
--- a/studio.view.ts
+++ b/studio.view.ts
@@ -214,7 +214,7 @@ namespace $.$$ {
 			const all = new Map< string, $mol_tree2 >()
 			
 			const add = ( prop: $mol_tree2 )=> {
-				const name = this.$.$mol_view_tree2_prop_split( prop ).name.text()
+				const name = this.$.$mol_view_tree2_prop_parts( prop ).name
 				all.set( name, prop )
 			}
 
@@ -262,7 +262,7 @@ namespace $.$$ {
 		@ $mol_mem
 		props() {
 			const props = this.prop_filtered().map( prop => {
-				const name = this.$.$mol_view_tree2_prop_split( prop ).name.text()
+				const name = this.$.$mol_view_tree2_prop_parts( prop ).name
 				return this.Prop( name )
 			} )
 			return props
diff --git a/type/type.view.tree b/type/type.view.tree
index 6c811ee..f8044c2 100644
--- a/type/type.view.tree
+++ b/type/type.view.tree
@@ -1,6 +1,7 @@
 $hyoo_studio_type $mol_pick
-	tree?val $mol_tree2_empty
+	tree?val null $mol_tree2_empty
 	belong_to \
+	type? \
 	trigger_content /
 		<= Value $mol_paragraph title <= type_display \
 		<= Take_put_hack_icon $mol_icon_arrow_left_right_bold_outline
diff --git a/type/type.view.ts b/type/type.view.ts
index 45e30b9..9bc561f 100644
--- a/type/type.view.ts
+++ b/type/type.view.ts
@@ -103,32 +103,36 @@ namespace $.$$ {
 
 		@ $mol_mem
 		type( next? : string ) {
-			
-			if( next !== undefined ) {
-
-				switch( next ) {
-					case '' : this.tree(null); break
-					case 'null' : this.tree( this.tree().struct('null') ); break
-					case 'boolean_true' : this.tree( this.tree().struct('true') ); break
-					case 'boolean_false' : this.tree( this.tree().struct('false') ); break
-					case 'number': this.tree( this.tree().struct('0') ); break
-					case 'number_nan': this.tree( this.tree().struct('+NaN') ); break
-					case 'number_infinity_negative': this.tree( this.tree().struct('-Infinity') ); break
-					case 'number_infinity_positive': this.tree( this.tree().struct('+Infinity') ); break
-					case 'text': this.tree( this.tree().data('') ); break
-					case 'list': this.tree( this.tree().struct( '/' ) ); break
-					case 'dict': this.tree( this.tree().struct( '*' ) ); break
-					case 'object': this.tree( this.tree().struct( '$mol_view', [ this.tree().kids[0] ?? this.tree().data( '' ) ] ) ); break
-					case 'bind': this.tree( this.tree().struct( '<=>', [ this.tree().kids[0] ?? this.tree().data( '' ) ] ) ); break
-					case 'get': this.tree( this.tree().struct( '<=', [ this.tree().kids[0] ?? this.tree().data( '' ) ] ) ); break
-					case 'put': this.tree( this.tree().struct( '=>', [ this.tree().kids[0] ?? this.tree().data( '' ) ] ) ); break
-					default : $mol_fail( new TypeError( `Unsupported type: ${ next }` ) )
-				}
-
-				this.showed(false)
+			const tree = this.tree()
+			if (! tree) throw new Error(`tree prop not provided`)
+			if (next === undefined) return $hyoo_studio_type_value(tree)
+
+			let val
+
+			switch( next ) {
+				case '' : val = null; break
+				case 'null' : val = tree.struct('null'); break
+				case 'boolean_true' : val = tree.struct('true'); break
+				case 'boolean_false' : val = tree.struct('false'); break
+				case 'number': val = tree.struct('0'); break
+				case 'number_nan': val = tree.struct('+NaN'); break
+				case 'number_infinity_negative': val = tree.struct('-Infinity'); break
+				case 'number_infinity_positive': val = tree.struct('+Infinity'); break
+				case 'text': val = tree.data(''); break
+				case 'list': val = tree.struct( '/' ); break
+				case 'dict': val = tree.struct( '*' ); break
+				case 'object': val = tree.struct( '$mol_view', [ tree.kids[0] ?? tree.data( '' ) ] ); break
+				case 'bind': val = tree.struct( '<=>', [ tree.kids[0] ?? tree.data( '' ) ] ); break
+				case 'get': val = tree.struct( '<=', [ tree.kids[0] ?? tree.data( '' ) ] ); break
+				case 'put': val = tree.struct( '=>', [ tree.kids[0] ?? tree.data( '' ) ] ); break
 			}
 
-			return $hyoo_studio_type_value(this.tree())
+			if (val === undefined) $mol_fail( new TypeError( `Unsupported type: ${ next }` ) )
+
+			const next_tree = this.tree(val)!
+			this.showed(false)
+
+			return $hyoo_studio_type_value(next_tree)
 		}
 
 		show_obj_select() {
@@ -140,10 +144,10 @@ namespace $.$$ {
 
 			if ( next !== undefined ) {
 				this.showed(false)
-				return this.tree(this.tree().struct( next )).type
+				return this.tree(this.tree()?.struct( next ))?.type ?? super.selected_class()
 			}
 			
-			return this.tree()?.type
+			return this.tree()?.type ?? super.selected_class()
 		}
 		
 		@ $mol_mem
@@ -156,8 +160,8 @@ namespace $.$$ {
 			const from_tree = this.tree(
 				next === undefined
 					? undefined
-					: this.tree().struct( '/' + next, this.tree().kids )
-			).type.slice( 1 )
+					: this.tree()?.struct( '/' + next, this.tree()?.kids ?? []) ?? null
+			)?.type.slice( 1 )
 
 			const focused = this.List_items_type().focused()
 
diff --git a/value/bound/bound.view.ts b/value/bound/bound.view.ts
index a34b354..168815c 100644
--- a/value/bound/bound.view.ts
+++ b/value/bound/bound.view.ts
@@ -42,7 +42,7 @@ namespace $.$$ {
 			const val = this.tree()
 			
 			if( next === undefined ) {
-				return this.$.$mol_view_tree2_prop_split( val.kids[ 0 ] ).name.text() || '...'
+				return this.$.$mol_view_tree2_prop_parts( val.kids[ 0 ] ).name || '...'
 			}
 			
 			this.tree(