diff --git a/uidev/src/testbed/testbed_generic.rs b/uidev/src/testbed/testbed_generic.rs
index c1015fd..67c3cdd 100644
--- a/uidev/src/testbed/testbed_generic.rs
+++ b/uidev/src/testbed/testbed_generic.rs
@@ -194,7 +194,7 @@ impl TestbedGeneric {
 		layout: &mut Layout,
 		data: &mut Data,
 	) -> anyhow::Result<()> {
-		data.popup_window.open(WguiWindowParams {
+		data.popup_window.open(&mut WguiWindowParams {
 			globals: self.globals.clone(),
 			position: Vec2::new(128.0, 128.0),
 			layout,
diff --git a/wgui/assets/wgui/window_frame.xml b/wgui/assets/wgui/window_frame.xml
index d836a3b..6f07a75 100644
--- a/wgui/assets/wgui/window_frame.xml
+++ b/wgui/assets/wgui/window_frame.xml
@@ -17,9 +17,8 @@
       </rectangle>
 
       <!-- content itself -->
-      <div width="100%" height="100%" padding="8" gap="4" flex_direction="column">
-        <label text="Window content" />
-        <Button id="button" color="#9911AA" text="I'm clickable." width="128" height="24" />
+      <div id="content" width="100%" height="100%" padding="8" gap="4" flex_direction="column">
+
       </div>
     </rectangle>
   </elements>
diff --git a/wgui/src/components/button.rs b/wgui/src/components/button.rs
index bb1ed21..894a228 100644
--- a/wgui/src/components/button.rs
+++ b/wgui/src/components/button.rs
@@ -3,15 +3,14 @@ use crate::{
 	components::{Component, ComponentBase, ComponentTrait, InitData},
 	drawing::{self, Boundary, Color},
 	event::{CallbackDataCommon, EventListenerCollection, EventListenerKind, ListenerHandleVec},
-	globals::Globals,
 	i18n::Translation,
-	layout::{Layout, WidgetID, WidgetPair},
+	layout::{WidgetID, WidgetPair},
 	renderer_vk::{
 		text::{FontWeight, TextStyle},
 		util::centered_matrix,
 	},
 	widget::{
-		EventResult, WidgetData,
+		ConstructEssentials, EventResult, WidgetData,
 		label::{WidgetLabel, WidgetLabelParams},
 		rectangle::{WidgetRectangle, WidgetRectangleParams},
 		util::WLength,
@@ -267,12 +266,10 @@ fn register_event_mouse_release<U1, U2>(
 }
 
 pub fn construct<U1, U2>(
-	globals: &mut Globals,
-	layout: &mut Layout,
-	listeners: &mut EventListenerCollection<U1, U2>,
-	parent: WidgetID,
+	ess: ConstructEssentials<U1, U2>,
 	params: Params,
 ) -> anyhow::Result<(WidgetPair, Rc<ComponentButton>)> {
+	let globals = ess.layout.state.globals.clone();
 	let mut style = params.style;
 
 	// force-override style
@@ -285,7 +282,7 @@ pub fn construct<U1, U2>(
 	let color = if let Some(color) = params.color {
 		color
 	} else {
-		globals.defaults.button_color
+		globals.get().defaults.button_color
 	};
 
 	let border_color = if let Some(border_color) = params.border_color {
@@ -306,8 +303,8 @@ pub fn construct<U1, U2>(
 		Color::new(color.r + 0.5, color.g + 0.5, color.g + 0.5, color.a + 0.5)
 	};
 
-	let (root, _) = layout.add_child(
-		parent,
+	let (root, _) = ess.layout.add_child(
+		ess.parent,
 		WidgetRectangle::create(WidgetRectangleParams {
 			color,
 			color2: get_color2(&color),
@@ -324,10 +321,10 @@ pub fn construct<U1, U2>(
 	let light_text = (color.r + color.g + color.b) < 1.5;
 
 	let id_label = if let Some(content) = params.text {
-		let (label, _node_label) = layout.add_child(
+		let (label, _node_label) = ess.layout.add_child(
 			id_rect,
 			WidgetLabel::create(
-				globals,
+				&mut globals.get(),
 				WidgetLabelParams {
 					content,
 					style: TextStyle {
@@ -365,13 +362,13 @@ pub fn construct<U1, U2>(
 
 	let mut base = ComponentBase::default();
 
-	register_event_mouse_enter(data.clone(), state.clone(), listeners, &mut base.lhandles);
-	register_event_mouse_leave(data.clone(), state.clone(), listeners, &mut base.lhandles);
-	register_event_mouse_press(data.clone(), state.clone(), listeners, &mut base.lhandles);
-	register_event_mouse_release(data.clone(), state.clone(), listeners, &mut base.lhandles);
+	register_event_mouse_enter(data.clone(), state.clone(), ess.listeners, &mut base.lhandles);
+	register_event_mouse_leave(data.clone(), state.clone(), ess.listeners, &mut base.lhandles);
+	register_event_mouse_press(data.clone(), state.clone(), ess.listeners, &mut base.lhandles);
+	register_event_mouse_release(data.clone(), state.clone(), ess.listeners, &mut base.lhandles);
 
 	let button = Rc::new(ComponentButton { base, data, state });
 
-	layout.defer_component_init(Component(button.clone()));
+	ess.layout.defer_component_init(Component(button.clone()));
 	Ok((root, button))
 }
diff --git a/wgui/src/components/checkbox.rs b/wgui/src/components/checkbox.rs
index 81c94f9..60e3286 100644
--- a/wgui/src/components/checkbox.rs
+++ b/wgui/src/components/checkbox.rs
@@ -10,10 +10,10 @@ use crate::{
 	drawing::Color,
 	event::{CallbackDataCommon, EventAlterables, EventListenerCollection, EventListenerKind, ListenerHandleVec},
 	i18n::Translation,
-	layout::{self, Layout, LayoutState, WidgetID, WidgetPair},
+	layout::{self, LayoutState, WidgetID, WidgetPair},
 	renderer_vk::text::{FontWeight, TextStyle},
 	widget::{
-		EventResult,
+		ConstructEssentials, EventResult,
 		label::{WidgetLabel, WidgetLabelParams},
 		rectangle::{WidgetRectangle, WidgetRectangleParams},
 		util::WLength,
@@ -248,9 +248,7 @@ fn register_event_mouse_release<U1, U2>(
 }
 
 pub fn construct<U1, U2>(
-	layout: &mut Layout,
-	listeners: &mut EventListenerCollection<U1, U2>,
-	parent: WidgetID,
+	ess: ConstructEssentials<U1, U2>,
 	params: Params,
 ) -> anyhow::Result<(WidgetPair, Rc<ComponentCheckbox>)> {
 	let mut style = params.style;
@@ -268,10 +266,10 @@ pub fn construct<U1, U2>(
 	//style.align_self = Some(taffy::AlignSelf::Start); // do not stretch self to the parent
 	style.gap = length(4.0);
 
-	let globals = layout.state.globals.clone();
+	let globals = ess.layout.state.globals.clone();
 
-	let (root, _) = layout.add_child(
-		parent,
+	let (root, _) = ess.layout.add_child(
+		ess.parent,
 		WidgetRectangle::create(WidgetRectangleParams {
 			color: Color::new(1.0, 1.0, 1.0, 0.0),
 			border_color: Color::new(1.0, 1.0, 1.0, 0.0),
@@ -288,7 +286,7 @@ pub fn construct<U1, U2>(
 		height: length(params.box_size),
 	};
 
-	let (outer_box, _) = layout.add_child(
+	let (outer_box, _) = ess.layout.add_child(
 		id_container,
 		WidgetRectangle::create(WidgetRectangleParams {
 			border: 2.0,
@@ -306,7 +304,7 @@ pub fn construct<U1, U2>(
 		},
 	)?;
 
-	let (inner_box, _) = layout.add_child(
+	let (inner_box, _) = ess.layout.add_child(
 		outer_box.id,
 		WidgetRectangle::create(WidgetRectangleParams {
 			round: WLength::Units(5.0),
@@ -322,7 +320,7 @@ pub fn construct<U1, U2>(
 		},
 	)?;
 
-	let (label, _node_label) = layout.add_child(
+	let (label, _node_label) = ess.layout.add_child(
 		id_container,
 		WidgetLabel::create(
 			&mut globals.get(),
@@ -352,13 +350,13 @@ pub fn construct<U1, U2>(
 
 	let mut base = ComponentBase::default();
 
-	register_event_mouse_enter(&data, state.clone(), listeners, &mut base.lhandles);
-	register_event_mouse_leave(&data, state.clone(), listeners, &mut base.lhandles);
-	register_event_mouse_press(&data, state.clone(), listeners, &mut base.lhandles);
-	register_event_mouse_release(data.clone(), state.clone(), listeners, &mut base.lhandles);
+	register_event_mouse_enter(&data, state.clone(), ess.listeners, &mut base.lhandles);
+	register_event_mouse_leave(&data, state.clone(), ess.listeners, &mut base.lhandles);
+	register_event_mouse_press(&data, state.clone(), ess.listeners, &mut base.lhandles);
+	register_event_mouse_release(data.clone(), state.clone(), ess.listeners, &mut base.lhandles);
 
 	let checkbox = Rc::new(ComponentCheckbox { base, data, state });
 
-	layout.defer_component_init(Component(checkbox.clone()));
+	ess.layout.defer_component_init(Component(checkbox.clone()));
 	Ok((root, checkbox))
 }
diff --git a/wgui/src/components/slider.rs b/wgui/src/components/slider.rs
index a59195e..e4d7b60 100644
--- a/wgui/src/components/slider.rs
+++ b/wgui/src/components/slider.rs
@@ -9,13 +9,13 @@ use crate::{
 	drawing::{self},
 	event::{self, CallbackDataCommon, EventListenerCollection, EventListenerKind, ListenerHandleVec},
 	i18n::Translation,
-	layout::{Layout, WidgetID, WidgetPair},
+	layout::{WidgetID, WidgetPair},
 	renderer_vk::{
 		text::{FontWeight, HorizontalAlign, TextStyle},
 		util,
 	},
 	widget::{
-		EventResult,
+		ConstructEssentials, EventResult,
 		div::WidgetDiv,
 		label::{WidgetLabel, WidgetLabelParams},
 		rectangle::{WidgetRectangle, WidgetRectangleParams},
@@ -308,9 +308,7 @@ fn register_event_mouse_release<U1, U2>(
 }
 
 pub fn construct<U1, U2>(
-	layout: &mut Layout,
-	listeners: &mut EventListenerCollection<U1, U2>,
-	parent: WidgetID,
+	ess: ConstructEssentials<U1, U2>,
 	params: Params,
 ) -> anyhow::Result<(WidgetPair, Rc<ComponentSlider>)> {
 	let mut style = params.style;
@@ -318,10 +316,10 @@ pub fn construct<U1, U2>(
 	style.min_size = style.size;
 	style.max_size = style.size;
 
-	let (root, slider_body_node) = layout.add_child(parent, WidgetDiv::create(), style)?;
+	let (root, slider_body_node) = ess.layout.add_child(ess.parent, WidgetDiv::create(), style)?;
 	let body_id = root.id;
 
-	let (_background_id, _) = layout.add_child(
+	let (_background_id, _) = ess.layout.add_child(
 		body_id,
 		WidgetRectangle::create(WidgetRectangleParams {
 			color: BODY_COLOR,
@@ -354,9 +352,11 @@ pub fn construct<U1, U2>(
 	};
 
 	// invisible outer handle body
-	let (slider_handle, slider_handle_node) = layout.add_child(body_id, WidgetDiv::create(), slider_handle_style)?;
+	let (slider_handle, slider_handle_node) = ess
+		.layout
+		.add_child(body_id, WidgetDiv::create(), slider_handle_style)?;
 
-	let (slider_handle_rect, _) = layout.add_child(
+	let (slider_handle_rect, _) = ess.layout.add_child(
 		slider_handle.id,
 		WidgetRectangle::create(WidgetRectangleParams {
 			color: HANDLE_COLOR,
@@ -381,9 +381,9 @@ pub fn construct<U1, U2>(
 		values: params.values,
 	};
 
-	let globals = layout.state.globals.clone();
+	let globals = ess.layout.state.globals.clone();
 
-	let (slider_text, _) = layout.add_child(
+	let (slider_text, _) = ess.layout.add_child(
 		slider_handle.id,
 		WidgetLabel::create(
 			&mut globals.get(),
@@ -412,15 +412,15 @@ pub fn construct<U1, U2>(
 
 	let mut base = ComponentBase::default();
 
-	register_event_mouse_enter(data.clone(), state.clone(), listeners, &mut base.lhandles);
-	register_event_mouse_leave(data.clone(), state.clone(), listeners, &mut base.lhandles);
-	register_event_mouse_motion(data.clone(), state.clone(), listeners, &mut base.lhandles);
-	register_event_mouse_press(data.clone(), state.clone(), listeners, &mut base.lhandles);
-	register_event_mouse_leave(data.clone(), state.clone(), listeners, &mut base.lhandles);
-	register_event_mouse_release(&data, state.clone(), listeners, &mut base.lhandles);
+	register_event_mouse_enter(data.clone(), state.clone(), ess.listeners, &mut base.lhandles);
+	register_event_mouse_leave(data.clone(), state.clone(), ess.listeners, &mut base.lhandles);
+	register_event_mouse_motion(data.clone(), state.clone(), ess.listeners, &mut base.lhandles);
+	register_event_mouse_press(data.clone(), state.clone(), ess.listeners, &mut base.lhandles);
+	register_event_mouse_leave(data.clone(), state.clone(), ess.listeners, &mut base.lhandles);
+	register_event_mouse_release(&data, state.clone(), ess.listeners, &mut base.lhandles);
 
 	let slider = Rc::new(ComponentSlider { base, data, state });
 
-	layout.defer_component_init(Component(slider.clone()));
+	ess.layout.defer_component_init(Component(slider.clone()));
 	Ok((root, slider))
 }
diff --git a/wgui/src/layout.rs b/wgui/src/layout.rs
index d3396fb..412a827 100644
--- a/wgui/src/layout.rs
+++ b/wgui/src/layout.rs
@@ -53,6 +53,7 @@ impl WeakWidget {
 pub struct WidgetMap(HopSlotMap<WidgetID, Widget>);
 pub type WidgetNodeMap = SecondaryMap<WidgetID, taffy::NodeId>;
 
+#[derive(Clone)]
 pub struct WidgetPair {
 	pub id: WidgetID,
 	pub widget: Widget,
diff --git a/wgui/src/parser/component_button.rs b/wgui/src/parser/component_button.rs
index f5c76d0..1df2081 100644
--- a/wgui/src/parser/component_button.rs
+++ b/wgui/src/parser/component_button.rs
@@ -7,7 +7,7 @@ use crate::{
 		AttribPair, ParserContext, ParserFile, parse_check_f32, parse_children, process_component,
 		style::{parse_color_opt, parse_round, parse_style, parse_text_style},
 	},
-	widget::util::WLength,
+	widget::{ConstructEssentials, util::WLength},
 };
 
 pub fn parse_component_button<'a, U1, U2>(
@@ -60,13 +60,12 @@ pub fn parse_component_button<'a, U1, U2>(
 		}
 	}
 
-	let globals = ctx.layout.state.globals.clone();
-
 	let (widget, component) = button::construct(
-		&mut globals.get(),
-		ctx.layout,
-		ctx.listeners,
-		parent_id,
+		ConstructEssentials {
+			layout: ctx.layout,
+			listeners: ctx.listeners,
+			parent: parent_id,
+		},
 		button::Params {
 			color,
 			border,
diff --git a/wgui/src/parser/component_checkbox.rs b/wgui/src/parser/component_checkbox.rs
index c7d736f..2df2212 100644
--- a/wgui/src/parser/component_checkbox.rs
+++ b/wgui/src/parser/component_checkbox.rs
@@ -3,6 +3,7 @@ use crate::{
 	i18n::Translation,
 	layout::WidgetID,
 	parser::{AttribPair, ParserContext, parse_check_f32, parse_check_i32, process_component, style::parse_style},
+	widget::ConstructEssentials,
 };
 
 pub fn parse_component_checkbox<U1, U2>(
@@ -36,9 +37,11 @@ pub fn parse_component_checkbox<U1, U2>(
 	}
 
 	let (widget, component) = checkbox::construct(
-		ctx.layout,
-		ctx.listeners,
-		parent_id,
+		ConstructEssentials {
+			layout: ctx.layout,
+			listeners: ctx.listeners,
+			parent: parent_id,
+		},
 		checkbox::Params {
 			box_size,
 			text: translation,
diff --git a/wgui/src/parser/component_slider.rs b/wgui/src/parser/component_slider.rs
index 7904e26..29d2211 100644
--- a/wgui/src/parser/component_slider.rs
+++ b/wgui/src/parser/component_slider.rs
@@ -2,6 +2,7 @@ use crate::{
 	components::{Component, slider},
 	layout::WidgetID,
 	parser::{AttribPair, ParserContext, parse_check_f32, process_component, style::parse_style},
+	widget::ConstructEssentials,
 };
 
 pub fn parse_component_slider<U1, U2>(
@@ -32,9 +33,11 @@ pub fn parse_component_slider<U1, U2>(
 	}
 
 	let (widget, component) = slider::construct(
-		ctx.layout,
-		ctx.listeners,
-		parent_id,
+		ConstructEssentials {
+			layout: ctx.layout,
+			listeners: ctx.listeners,
+			parent: parent_id,
+		},
 		slider::Params {
 			style,
 			values: slider::ValuesMinMax {
diff --git a/wgui/src/widget/mod.rs b/wgui/src/widget/mod.rs
index c602477..8500318 100644
--- a/wgui/src/widget/mod.rs
+++ b/wgui/src/widget/mod.rs
@@ -6,8 +6,8 @@ use crate::{
 	any::AnyTrait,
 	drawing::{self, PrimitiveExtent},
 	event::{
-		self, CallbackData, CallbackDataCommon, CallbackMetadata, Event, EventAlterables, EventListenerKind,
-		EventListenerVec, MouseWheelEvent,
+		self, CallbackData, CallbackDataCommon, CallbackMetadata, Event, EventAlterables, EventListenerCollection,
+		EventListenerKind, EventListenerVec, MouseWheelEvent,
 	},
 	layout::{Layout, LayoutState, WidgetID},
 	stack::{ScissorStack, TransformStack},
@@ -516,3 +516,9 @@ impl WidgetState {
 		Ok(EventResult::Pass)
 	}
 }
+
+pub struct ConstructEssentials<'a, U1, U2> {
+	pub layout: &'a mut Layout,
+	pub listeners: &'a mut EventListenerCollection<U1, U2>,
+	pub parent: WidgetID,
+}
diff --git a/wgui/src/windowing.rs b/wgui/src/windowing.rs
index 59a5eaa..858238b 100644
--- a/wgui/src/windowing.rs
+++ b/wgui/src/windowing.rs
@@ -16,6 +16,7 @@ use crate::{
 struct OpenedWindow {
 	layout_tasks: LayoutTasks,
 	widget: WidgetPair,
+	content: WidgetPair,
 
 	#[allow(dead_code)]
 	state: ParserState,
@@ -34,6 +35,10 @@ struct State {
 #[derive(Clone)]
 pub struct WguiWindow(Rc<RefCell<State>>);
 
+pub struct OnContentData {
+	pub widget: WidgetPair,
+}
+
 pub struct WguiWindowParams<'a> {
 	pub position: Vec2,
 	pub globals: WguiGlobals,
@@ -52,7 +57,7 @@ impl WguiWindow {
 		self.0.borrow_mut().opened_window = None;
 	}
 
-	pub fn open(&mut self, params: WguiWindowParams) -> anyhow::Result<()> {
+	pub fn open(&mut self, params: &mut WguiWindowParams) -> anyhow::Result<()> {
 		// close previous one if it's already open
 		self.close();
 
@@ -74,7 +79,7 @@ impl WguiWindow {
 
 		let state = parser::parse_from_assets(
 			&parser::ParseDocumentParams {
-				globals: params.globals,
+				globals: params.globals.clone(),
 				path: XML_PATH,
 				extra: Default::default(),
 			},
@@ -92,19 +97,20 @@ impl WguiWindow {
 			})
 		});
 
-		let button = state.fetch_component_as::<ComponentButton>("button").unwrap();
-
-		button.on_click(Box::new(move |_common, _e| {
-			log::info!("click");
-			Ok(())
-		}));
+		let content = state.fetch_widget(&params.layout.state, "content")?;
 
 		self.0.borrow_mut().opened_window = Some(OpenedWindow {
 			widget,
 			state,
 			layout_tasks: params.layout.tasks.clone(),
+			content,
 		});
 
 		Ok(())
 	}
+
+	pub fn get_content(&self) -> WidgetPair {
+		let state = self.0.borrow_mut();
+		state.opened_window.as_ref().unwrap().content.clone()
+	}
 }