diff --git a/crates/ui-egui/src/dialogs/shapes.rs b/crates/ui-egui/src/dialogs/shapes.rs
index 9df9280cc..55181043b 100644
--- a/crates/ui-egui/src/dialogs/shapes.rs
+++ b/crates/ui-egui/src/dialogs/shapes.rs
@@ -2,10 +2,13 @@
 //! Star, Line Segment Tool Options and the two grids (size, divider counts and skews, switches).
 
 use serde_json::{Value, json};
+use vectorcraft_geom::{Point, Rect};
 
 use super::{DialogSpec, form, run_and_close};
 use crate::VectorcraftApp;
+use crate::panels::transform::artboard_rect;
 use crate::state::Dialog;
+use crate::widgets;
 
 pub(super) const SPEC: DialogSpec = DialogSpec { heading: |d| title(&d.kind).into(), body, confirm, ..DialogSpec::FORM };
 
@@ -27,9 +30,57 @@ fn grid_keys(kind: &str) -> ([&'static str; 2], [&'static str; 2]) {
     if kind == "polarGrid" { (["concentric", "radial"], ["concentricSkew", "radialSkew"]) } else { (["rows", "columns"], ["rowSkew", "columnSkew"]) }
 }
 
+/// The 9-point locator index for a grid dialog (`reference`, default top-left).
+fn grid_reference(d: &Dialog) -> usize {
+    d.fields.get("reference").and_then(|v| v.as_u64()).map(|n| (n as usize).min(8)).unwrap_or(0)
+}
+
+/// A grid dialog's bounding box from its top-left `x`/`y` and size fields.
+fn grid_placed(d: &Dialog) -> Rect {
+    let (x, y) = (d.f64("x", 0.0), d.f64("y", 0.0));
+    Rect::new(x, y, x + d.f64("width", 100.0), y + d.f64("height", 100.0))
+}
+
+fn set_grid_placed(d: &mut Dialog, r: Rect) {
+    d.fields.insert("x".into(), json!(r.x0));
+    d.fields.insert("y".into(), json!(r.y0));
+    d.fields.insert("width".into(), json!(r.width()));
+    d.fields.insert("height".into(), json!(r.height()));
+}
+
+/// Top-left `x`/`y` so reference point `refi` sits on the canvas click (`__anchorX`/`__anchorY`).
+pub(crate) fn grid_pin_to_anchor(d: &mut Dialog) {
+    let anchor = Point::new(d.f64("__anchorX", d.f64("x", 0.0)), d.f64("__anchorY", d.f64("y", 0.0)));
+    let refi = grid_reference(d);
+    let (w, h) = (d.f64("width", 100.0), d.f64("height", 100.0));
+    let rp = vectorcraft_geom::reference_point(Rect::new(0.0, 0.0, w, h), refi);
+    d.fields.insert("x".into(), json!(anchor.x - rp.x));
+    d.fields.insert("y".into(), json!(anchor.y - rp.y));
+}
+
 /// The form's fields, then a grid's switches.
 fn body(app: &mut VectorcraftApp, ui: &mut egui::Ui, d: &mut Dialog) -> bool {
-    form::grid(ui, d, app.session.general_unit());
+    let unit = app.session.general_unit();
+    if matches!(d.kind.as_str(), "rectangularGrid" | "polarGrid") {
+        ui.horizontal(|ui| {
+            let refi = grid_reference(d);
+            if let Some(i) = widgets::reference_point(ui, refi) {
+                d.fields.insert("reference".into(), json!(i));
+                grid_pin_to_anchor(d);
+            }
+        });
+        ui.add_space(4.0);
+        let refi = grid_reference(d);
+        let (was, w0, h0) = (grid_placed(d), d.f64("width", 100.0), d.f64("height", 100.0));
+        form::grid_then(ui, d, unit, |_, d| {
+            let (w, h) = (d.f64("width", 100.0), d.f64("height", 100.0));
+            if (w - w0).abs() > 1e-9 || (h - h0).abs() > 1e-9 {
+                set_grid_placed(d, artboard_rect(was, refi, None, None, Some(w), Some(h), false));
+            }
+        });
+    } else {
+        form::grid(ui, d, unit);
+    }
     let own = match d.kind.as_str() {
         "rectangularGrid" => ("frame", tl!("Use Outside Rectangle As Frame")),
         "polarGrid" => ("compound", tl!("Create Compound Path From Ellipses")),
@@ -54,8 +105,9 @@ fn confirm(app: &mut VectorcraftApp, d: &Dialog) -> Result<Value, String> {
         kind @ ("rectangularGrid" | "polarGrid") => {
             // The switches as they are; the typed fields as numbers.
             let (mut p, (counts, skews)) = (form::params(d), grid_keys(kind));
-            for (k, default) in [("width", 100.0), ("height", 100.0)] {
-                p[k] = json!(d.f64(k, default));
+            let r = grid_placed(d);
+            for (k, v) in [("x", r.x0), ("y", r.y0), ("width", r.width()), ("height", r.height())] {
+                p[k] = json!(v);
             }
             for (count, skew) in counts.into_iter().zip(skews) {
                 p[count] = json!((d.f64(count, 5.0) as u64).min(999));
diff --git a/crates/ui-egui/src/dialogs/tests_rectangular_grid.rs b/crates/ui-egui/src/dialogs/tests_rectangular_grid.rs
index 8d9f8c56b..8c6f6331e 100644
--- a/crates/ui-egui/src/dialogs/tests_rectangular_grid.rs
+++ b/crates/ui-egui/src/dialogs/tests_rectangular_grid.rs
@@ -159,6 +159,31 @@ fn key_frame(app: &mut VectorcraftApp, key: egui::Key) {
     out.textures_delta.clear();
 }
 
+#[test]
+fn rectangular_grid_reference_locator_reanchors_to_the_click() {
+    let mut app = app();
+    click(&mut app, Point::new(100.0, 100.0));
+    set(&mut app, "reference", json!(4));
+    super::shapes::grid_pin_to_anchor(app.ui.dialog.as_mut().unwrap());
+    assert_eq!((field(&app, "x"), field(&app, "y")), (json!(50.0), json!(50.0)));
+    let id = confirm(&mut app);
+    assert_grid(&app, id, Rect::new(50.0, 50.0, 150.0, 150.0), 5, 5);
+}
+
+/// #1377: OK uses the bounding box after a reference-point resize (`artboard_rect` keeps the
+/// center pinned when width doubles).
+#[test]
+fn rectangular_grid_reference_point_pins_center_when_width_changes() {
+    let mut app = app();
+    click(&mut app, Point::new(100.0, 100.0));
+    assert_eq!(field(&app, "reference"), json!(0));
+    for (key, value) in [("reference", json!(4)), ("x", json!(50.0)), ("y", json!(50.0)), ("width", json!(200)), ("height", json!(100))] {
+        set(&mut app, key, value);
+    }
+    let id = confirm(&mut app);
+    assert_grid(&app, id, Rect::new(50.0, 50.0, 250.0, 150.0), 5, 5);
+}
+
 #[test]
 fn rectangular_grid_canvas_click_opens_registered_dialog_with_saved_counts_and_point_defaults() {
     let mut app = app();
diff --git a/crates/ui-egui/src/dialogs/tools.rs b/crates/ui-egui/src/dialogs/tools.rs
index 034295ff3..0b1cd94d0 100644
--- a/crates/ui-egui/src/dialogs/tools.rs
+++ b/crates/ui-egui/src/dialogs/tools.rs
@@ -3,6 +3,7 @@
 
 use serde_json::{Value, json};
 
+use super::shapes::grid_pin_to_anchor;
 use crate::VectorcraftApp;
 use crate::state::Dialog;
 
@@ -18,11 +19,17 @@ pub fn open_tool_dialog(app: &mut VectorcraftApp, kind: &str, p: Value) {
         "lineSegment" => Dialog::new(kind, json!({"x": x, "y": y, "length": "100 pt", "angle": 0})),
         // The grids: the tool's stored options (divider counts and skews, switches) at the default size.
         "rectangularGrid" | "polarGrid" => {
-            let mut fields = app.session.tool_options_of(kind);
-            for (key, value) in [("x", json!(x)), ("y", json!(y)), ("width", json!("100 pt")), ("height", json!("100 pt"))] {
-                fields[key] = value;
+            let mut obj = match app.session.tool_options_of(kind) {
+                Value::Object(o) => o,
+                _ => serde_json::Map::new(),
+            };
+            for (key, value) in [("__anchorX", json!(x)), ("__anchorY", json!(y)), ("width", json!("100 pt")), ("height", json!("100 pt"))] {
+                obj.insert(key.into(), value);
             }
-            Dialog::new(kind, fields)
+            obj.insert("reference".into(), json!(0));
+            let mut d = Dialog::new(kind, Value::Object(obj));
+            grid_pin_to_anchor(&mut d);
+            d
         }
         // Graph tool click: the graph's size.
         "graph" => Dialog::new(