diff --git a/examples/electron_crystal.cpp b/examples/electron_crystal.cpp
deleted file mode 100644
index e3a6dde4..00000000
--- a/examples/electron_crystal.cpp
+++ /dev/null
@@ -1,406 +0,0 @@
-#include <psemek/app/app.hpp>
-#include <psemek/app/main.hpp>
-#include <psemek/gfx/painter.hpp>
-#include <psemek/geom/orthographic.hpp>
-#include <psemek/random/device.hpp>
-#include <psemek/random/generator.hpp>
-#include <psemek/random/uniform_ball.hpp>
-#include <psemek/cg/triangulation/delaunay.hpp>
-#include <psemek/util/clock.hpp>
-#include <psemek/prof/profiler.hpp>
-#include <psemek/app/ui_scene.hpp>
-#include <psemek/ui/button.hpp>
-#include <psemek/ui/slider.hpp>
-#include <psemek/ui/default_element_factory.hpp>
-#include <psemek/ui/frame.hpp>
-#include <psemek/ui/window.hpp>
-#include <psemek/ui/screen.hpp>
-#include <psemek/ui/grid_layout.hpp>
-#include <psemek/ui/event_interceptor.hpp>
-#include <psemek/util/to_string.hpp>
-#include <psemek/util/recursive.hpp>
-#include <psemek/util/moving_average.hpp>
-
-#include <vector>
-
-using namespace psemek;
-
-struct main_scene
-	: app::ui_scene
-{
-	main_scene(ui::controller & ui_controller);
-
-	void update() override;
-	void present() override;
-
-	float simulation_radius = 1.f;
-	float simulation_radius_tgt = 1.f;
-
-	float potential = 1000.f;
-	float step = 1e-4f;
-	float multipole_threshold = 2.f;
-
-	std::shared_ptr<ui::label> time_value_label;
-
-	random::generator rng{random::device{}};
-
-	std::vector<geom::point<float, 2>> points;
-	std::vector<geom::segment<std::uint32_t>> edges;
-	std::vector<std::uint32_t> degree;
-
-	gfx::painter painter;
-
-	util::clock<> clock;
-	util::moving_average<float> update_time{64};
-};
-
-main_scene::main_scene(ui::controller & ui_controller)
-	: app::ui_scene(ui_controller)
-{
-	ui::default_element_factory element_factory;
-
-	auto root = element_factory.make_screen();
-
-	auto wheel_event = std::make_shared<ui::event_interceptor>();
-	wheel_event->on_mouse_wheel([this](ui::mouse_wheel const & event){
-		simulation_radius_tgt *= std::pow(0.8f, event.delta);
-		return true;
-	});
-	wheel_event->set_child(element_factory.make_screen());
-	root->add_child(wheel_event, ui::screen::x_policy::fill, ui::screen::y_policy::fill);
-
-	auto panel = element_factory.make_window("");
-	panel->caption()->set_tagged_text("[bold][uline]Options[/uline][/bold]");
-	root->add_child(panel, ui::screen::x_policy::floating, ui::screen::y_policy::floating);
-
-	auto layout = element_factory.make_grid_layout();
-	panel->set_child(layout);
-
-	auto count_name_label = element_factory.make_label("Count:");
-	count_name_label->set_valign(ui::label::valignment::center);
-	count_name_label->set_halign(ui::label::halignment::right);
-	auto count_value_label = element_factory.make_label("");
-	count_value_label->set_valign(ui::label::valignment::center);
-	count_value_label->set_halign(ui::label::halignment::center);
-
-	auto count_slider = element_factory.make_slider();
-	count_slider->set_value_range({1, 5000}, false);
-	count_slider->on_value_changed([this, count_value_label](int value){
-		count_value_label->set_text(util::to_string(value));
-
-		if (value < points.size())
-			points.resize(value);
-		else
-		{
-			float radius = std::max(0.5f, std::sqrt((points.size() + value) / 1000.f));
-
-			random::uniform_sphere_point_distribution<float, 2> d({0.f, 0.f}, radius * 1.25f);
-			while (points.size() < value)
-				points.push_back(d(rng));
-		}
-	});
-	count_slider->set_value(100);
-
-	auto step_name_label = element_factory.make_label("Step:");
-	step_name_label->set_valign(ui::label::valignment::center);
-	step_name_label->set_halign(ui::label::halignment::right);
-	auto step_value_label = element_factory.make_label("");
-	step_value_label->set_valign(ui::label::valignment::center);
-	step_value_label->set_halign(ui::label::halignment::center);
-
-	auto step_slider = element_factory.make_slider();
-	step_slider->set_value_range({0, 12}, false);
-	step_slider->on_value_changed([this, step_value_label](int value){
-		step = std::pow(2.f, value - 20);
-		step_value_label->set_text(util::to_string(std::setprecision(1), std::scientific, step));
-	});
-	step_slider->set_value(11);
-
-	auto precision_name_label = element_factory.make_label("Precision:");
-	precision_name_label->set_valign(ui::label::valignment::center);
-	precision_name_label->set_halign(ui::label::halignment::right);
-	auto precision_value_label = element_factory.make_label("");
-	precision_value_label->set_valign(ui::label::valignment::center);
-	precision_value_label->set_halign(ui::label::halignment::center);
-
-	auto precision_slider = element_factory.make_slider();
-	precision_slider->set_value_range({5, 50}, false);
-	precision_slider->on_value_changed([this, precision_value_label](int value){
-		multipole_threshold = value * 0.1f;
-		precision_value_label->set_text(util::to_string(std::setprecision(1), std::fixed, multipole_threshold));
-	});
-	precision_slider->set_value(15);
-
-	auto time_name_label = element_factory.make_label("Computation time:");
-	time_name_label->set_valign(ui::label::valignment::center);
-	time_name_label->set_halign(ui::label::halignment::right);
-	time_value_label = element_factory.make_label("");
-	time_value_label->set_valign(ui::label::valignment::center);
-	time_value_label->set_halign(ui::label::halignment::center);
-
-	layout->set_size(4, 3);
-	layout->set_column_weight(0, 0.5f);
-	layout->set_column_weight(1, 0.5f);
-	layout->set(0, 0, count_name_label);
-	layout->set(0, 1, count_value_label);
-	layout->set(0, 2, count_slider);
-	layout->set(1, 0, step_name_label);
-	layout->set(1, 1, step_value_label);
-	layout->set(1, 2, step_slider);
-	layout->set(2, 0, precision_name_label);
-	layout->set(2, 1, precision_value_label);
-	layout->set(2, 2, precision_slider);
-	layout->set(3, 0, time_name_label);
-	layout->set(3, 1, time_value_label);
-
-	ui::style style;
-	style.font = ui::make_default_9x12_font();
-	style.bold_font = ui::make_default_10x12_bold_font();
-	style.text_scale = 1;
-	style.bg_color = gfx::color_rgba{127, 127, 191, 255};
-	style.fg_color = gfx::color_rgba{127, 127, 255, 255};
-	style.action_color = gfx::color_rgba{0, 0, 255, 255};
-	style.highlight_color = gfx::color_rgba{0, 255, 255, 255};
-	style.border_width = 0;
-	style.bevel_width = 0;
-	root->set_style(std::make_shared<ui::style>(std::move(style)));
-
-	set_ui(root);
-}
-
-struct node
-{
-	static constexpr std::uint32_t null = -1;
-
-	float size;
-	float mass = 0.f;
-	geom::point<float, 2> center = geom::point<float, 2>::zero();
-
-	std::uint32_t children[2][2] {{null, null}, {null, null}};
-};
-
-void main_scene::update()
-{
-	ui_scene::update();
-
-	float const dt = clock.restart().count();
-	const int iterations = 1;
-	auto const origin = geom::point<float, 2>::zero();
-
-	std::vector<node> nodes;
-	std::uint32_t root;
-
-	auto add_node = util::recursive([&](auto && self, geom::box<float, 2> const & bbox, auto begin, auto end) -> std::uint32_t
-	{
-		if (begin == end)
-			return node::null;
-
-		std::uint32_t id = nodes.size();
-		nodes.emplace_back().size = bbox[0].length();
-
-		if (end - begin > 1)
-		{
-			auto middle_x = bbox[0].center();
-			auto middle_y = bbox[1].center();
-
-			auto mid_it = std::partition(begin, end, [middle_x](auto const & p){ return p[0] < middle_x; });
-			auto left_mid_it = std::partition(begin, mid_it, [middle_y](auto const & p){ return p[1] < middle_y; });
-			auto right_mid_it = std::partition(mid_it, end, [middle_y](auto const & p){ return p[1] < middle_y; });
-
-			nodes[id].children[0][0] = self(geom::box<float, 2>{{{bbox[0].min, middle_x}, {bbox[1].min, middle_y}}}, begin, left_mid_it);
-			nodes[id].children[0][1] = self(geom::box<float, 2>{{{bbox[0].min, middle_x}, {middle_y, bbox[1].max}}}, left_mid_it, mid_it);
-			nodes[id].children[1][0] = self(geom::box<float, 2>{{{middle_x, bbox[0].max}, {bbox[1].min, middle_y}}}, mid_it, right_mid_it);
-			nodes[id].children[1][1] = self(geom::box<float, 2>{{{middle_x, bbox[0].max}, {middle_y, bbox[1].max}}}, right_mid_it, end);
-
-			geom::vector<float, 2> sum{0.f, 0.f};
-			for (int x : {0, 1})
-			{
-				for (int y : {0, 1})
-				{
-					auto cid = nodes[id].children[x][y];
-					if (cid != node::null)
-					{
-						nodes[id].mass += nodes[cid].mass;
-						sum += (nodes[cid].center - origin) * nodes[cid].mass;
-					}
-				}
-			}
-
-			nodes[id].center = origin + sum / nodes[id].mass;
-		}
-		else
-		{
-			nodes[id].mass = 1.f;
-			nodes[id].center = *begin;
-		}
-
-		return id;
-	});
-
-	{
-		float max_size = 0.f;
-		for (auto const & p : points)
-			geom::make_max(max_size, geom::distance(p, origin));
-
-		prof::profiler prof("tree");
-		root = add_node(geom::box<float, 2>{{{-max_size, max_size}, {-max_size, max_size}}}, points.begin(), points.end());
-	}
-
-	auto force_at = util::recursive([&](auto && self, auto const & p, auto id){
-		auto const & n = nodes[id];
-
-		if (n.center == p)
-			return geom::vector{0.f, 0.f};
-
-		auto d = p - n.center;
-
-		auto l = geom::length(d);
-
-		if (n.mass == 1.f || l > n.size * multipole_threshold)
-			return n.mass * d / std::pow(l, 3.f);
-
-		geom::vector sum{0.f, 0.f};
-
-		for (int x : {0, 1})
-		{
-			for (int y : {0, 1})
-			{
-				auto cid = nodes[id].children[x][y];
-				if (cid != node::null)
-					sum += self(p, cid);
-			}
-		}
-
-		return sum;
-	});
-
-	std::vector<geom::vector<float, 2>> delta;
-
-	for (int iteration = 0; iteration < iterations; ++iteration)
-	{
-		prof::profiler prof("descent");
-		delta.assign(points.size(), geom::vector<float, 2>::zero());
-
-		for (std::size_t i = 0; i < points.size(); ++i)
-			delta[i] += 2.f * potential * (origin - points[i]);
-
-		// Exact O(n^2) method
-//		for (std::size_t i = 0; i < points.size(); ++i)
-//		{
-//			for (std::size_t j = i + 1; j < points.size(); ++j)
-//			{
-//				auto d = points[i] - points[j];
-
-//				d /= std::pow(geom::length(d), 3.f);
-
-//				delta[i] += d;
-//				delta[j] -= d;
-//			}
-//		}
-
-		// Barnes-Hut algorithm
-		for (std::size_t i = 0; i < points.size(); ++i)
-			delta[i] += force_at(points[i], root);
-
-		for (std::size_t i = 0; i < points.size(); ++i)
-			points[i] += delta[i] * step * dt;
-	}
-
-	simulation_radius += (simulation_radius_tgt - simulation_radius) * (1.f - std::exp(-10.f * dt));
-
-	prof::profiler prof("delaunay");
-
-	auto const dcel = cg::delaunay<std::uint32_t>(geom::robust, points.begin(), points.end());
-
-	edges.clear();
-	degree.assign(points.size(), 0);
-	for (std::size_t i = 0; i < dcel.edges.size(); ++i)
-	{
-		auto const e = dcel.edge(i);
-		auto const v0 = e.origin().index();
-		auto const v1 = e.twin().origin().index();
-		if (v0 < v1)
-			edges.push_back({v0, v1});
-		degree[v0]++;
-	}
-
-	update_time.push(clock.count());
-	time_value_label->set_text(util::to_string(std::setprecision(3), std::fixed, update_time.average() * 1000.f, "ms"));
-}
-
-void main_scene::present()
-{
-	gl::ClearColor(1.f, 1.f, 1.f, 0.f);
-	gl::Clear(gl::COLOR_BUFFER_BIT | gl::DEPTH_BUFFER_BIT);
-
-	geom::box<float, 3> view_area;
-	{
-		view_area[0] = {-simulation_radius, simulation_radius};
-		view_area[1] = {-simulation_radius, simulation_radius};
-		view_area[2] = {-1.f, 1.f};
-
-		float const aspect_ratio = width() * 1.f / height();
-
-		float extra_y = view_area[1].length() * 0.1f;
-		view_area[1].min -= extra_y;
-		view_area[1].max += extra_y;
-		float extra_x = view_area[1].length() * aspect_ratio - view_area[0].length();
-		view_area[0].min -= extra_x / 2.f;
-		view_area[0].max += extra_x / 2.f;
-	}
-
-	geom::matrix<float, 4, 4> const transform = geom::orthographic{view_area}.homogeneous_matrix();
-
-	float const pixel_size = view_area[0].length() / width();
-
-	for (auto const & e : edges)
-		painter.line(points[e[0]], points[e[1]], 2.f * pixel_size, {127, 127, 127, 255}, false);
-
-	for (std::size_t i = 0; i < points.size(); ++i)
-	{
-		gfx::color_rgba color{0, 0, 0, 255};
-		int quality = 6;
-		if (degree[i] == 5)
-		{
-			quality = 3;
-			color = {255, 0, 0, 255};
-		}
-		else if (degree[i] == 7)
-		{
-			quality = 4;
-			color = {0, 0, 255, 255};
-		}
-		painter.circle(points[i], 6.f * pixel_size, color, quality);
-	}
-
-	painter.render(transform);
-
-	ui_scene::present();
-}
-
-struct electron_crystal_app
-	: app::app
-{
-	electron_crystal_app();
-	~electron_crystal_app();
-
-	async::event_loop event_loop;
-	ui::controller ui_controller;
-};
-
-electron_crystal_app::electron_crystal_app()
-	: app("Electron crystal simulation", 4)
-	, ui_controller(&event_loop)
-{
-	push_scene(std::make_shared<main_scene>(ui_controller));
-}
-
-electron_crystal_app::~electron_crystal_app()
-{
-	prof::dump();
-}
-
-int main()
-{
-	return app::main<electron_crystal_app>();
-}