diff --git a/crates/ui-egui/src/panes.rs b/crates/ui-egui/src/panes.rs
index 30ba3ba80..ec6146018 100644
--- a/crates/ui-egui/src/panes.rs
+++ b/crates/ui-egui/src/panes.rs
@@ -185,16 +185,23 @@ fn format_chart(app: &mut SheetApp, ui: &mut Ui) {
         ui.horizontal_wrapped(|ui| {
             for (l, k, s) in [
                 ("Column", "column", ""),
-                ("Stacked", "column", "stacked"),
+                ("Stacked Column", "column", "stacked"),
+                ("100% Stacked Column", "column", "stacked100"),
                 ("Bar", "bar", ""),
+                ("Stacked Bar", "bar", "stacked"),
+                ("100% Stacked Bar", "bar", "stacked100"),
                 ("Line", "line", "markers"),
+                ("Stacked Line", "line", "stacked"),
                 ("Area", "area", ""),
+                ("Stacked Area", "area", "stacked"),
+                ("100% Stacked Area", "area", "stacked100"),
                 ("Pie", "pie", ""),
                 ("Doughnut", "doughnut", ""),
                 ("Scatter", "scatter", ""),
                 ("Radar", "radar", ""),
             ] {
-                if ui.button(l).clicked() {
+                let cur = chart.kind == gridcraft_engine::cmd::insert::chart_kind(k, s);
+                if ui.selectable_label(cur, l).clicked() {
                     app.run_or_alert("chart.set", json!({"chart": id, "type": k, "subtype": s}));
                 }
             }
diff --git a/crates/ui-egui/tests/it/format_chart_type.rs b/crates/ui-egui/tests/it/format_chart_type.rs
new file mode 100644
index 000000000..ae19e1091
--- /dev/null
+++ b/crates/ui-egui/tests/it/format_chart_type.rs
@@ -0,0 +1,91 @@
+//! The Format Chart Area pane's Chart Type section changes the chart's type and marks the current one.
+
+use egui::accesskit::{Role, Toggled};
+use egui_kittest::kittest::{NodeT, Queryable};
+use gridcraft_engine::Session;
+use gridcraft_engine::model::ChartKind;
+use gridcraft_ui_egui::SheetApp;
+use serde_json::json;
+
+type Harness = egui_kittest::Harness<'static, SheetApp>;
+
+/// A two-series chart made with `insert.chart`'s `type` `t` and `subtype` `sub`, with Format Chart Area open on its Chart Type section.
+fn open_chart_type(t: &str, sub: &str) -> (Harness, u32) {
+    let mut session = Session::new();
+    session.new_workbook();
+    session.execute("range.setValues", json!({"range": "A1", "values": [["Quarter", "North", "South"], ["Q1", 10, 30], ["Q2", 30, 10]]})).unwrap();
+    session.execute("selection.set", json!({"range": "A1:C3"})).unwrap();
+    let chart = session.execute("insert.chart", json!({"type": t, "subtype": sub, "at": "E3"})).unwrap();
+    let id = chart["chart"].as_u64().unwrap() as u32;
+    let mut h = crate::support::harness(session, 4);
+    h.state_mut().selected_chart = Some(id);
+    h.state_mut().grid.pane = Some("formatChart".into());
+    h.run_steps(2);
+    h.get_by_role_and_label(Role::DisclosureTriangle, "Chart Type").click();
+    h.run_steps(2);
+    (h, id)
+}
+
+fn kind(h: &Harness, id: u32) -> ChartKind {
+    h.state().session.active().unwrap().wb.active().unwrap().charts.iter().find(|c| c.id == id).unwrap().kind
+}
+
+/// Whether the pane's `label` button is drawn as the chart's current type. The pane sits on the
+/// right, past the Chart Type header's left edge; the ribbon's buttons are elsewhere.
+fn marked(h: &Harness, label: &str) -> bool {
+    let left = h.get_by_role_and_label(Role::DisclosureTriangle, "Chart Type").rect().left();
+    let button = h.get_all_by_role_and_label(Role::Button, label).find(|n| n.rect().left() >= left - 1.0).unwrap();
+    button.accesskit_node().toggled() == Some(Toggled::True)
+}
+
+fn click(h: &mut Harness, label: &str) {
+    let left = h.get_by_role_and_label(Role::DisclosureTriangle, "Chart Type").rect().left();
+    h.get_all_by_role_and_label(Role::Button, label).find(|n| n.rect().left() >= left - 1.0).unwrap().click();
+    h.run_steps(2);
+}
+
+#[test]
+fn chart_type_offers_the_stacked_and_hundred_percent_stacked_types() {
+    let (mut h, id) = open_chart_type("column", "");
+    for (label, want) in [
+        ("Stacked Column", ChartKind::ColumnStacked),
+        ("100% Stacked Column", ChartKind::ColumnStacked100),
+        ("Stacked Bar", ChartKind::BarStacked),
+        ("100% Stacked Bar", ChartKind::BarStacked100),
+        ("Stacked Line", ChartKind::LineStacked),
+        ("Stacked Area", ChartKind::AreaStacked),
+        ("100% Stacked Area", ChartKind::AreaStacked100),
+        ("Column", ChartKind::ColumnClustered),
+    ] {
+        click(&mut h, label);
+        assert_eq!(kind(&h, id), want, "{label} changes the chart's type");
+    }
+}
+
+#[test]
+fn chart_type_marks_the_chart_s_current_type() {
+    for (t, sub, label) in
+        [("bar", "stacked100", "100% Stacked Bar"), ("area", "stacked", "Stacked Area"), ("column", "", "Column"), ("line", "markers", "Line")]
+    {
+        let (h, _) = open_chart_type(t, sub);
+        for other in [
+            "Column",
+            "Stacked Column",
+            "100% Stacked Column",
+            "Bar",
+            "Stacked Bar",
+            "100% Stacked Bar",
+            "Line",
+            "Stacked Line",
+            "Area",
+            "Stacked Area",
+            "100% Stacked Area",
+            "Pie",
+            "Doughnut",
+            "Scatter",
+            "Radar",
+        ] {
+            assert_eq!(marked(&h, other), other == label, "{other} on a {t} {sub} chart");
+        }
+    }
+}
diff --git a/crates/ui-egui/tests/it/main.rs b/crates/ui-egui/tests/it/main.rs
index 75ab9e86e..3f9a03ecb 100644
--- a/crates/ui-egui/tests/it/main.rs
+++ b/crates/ui-egui/tests/it/main.rs
@@ -38,6 +38,7 @@ mod find_dialog_focus;
 mod floating_pictures;
 mod font_box_filter;
 mod font_size_box;
+mod format_chart_type;
 mod format_painter;
 mod formula_bar;
 mod formula_bar_expand;