From 5a7c56cdaa6c4de435f0f0c28d29c72b980348bd Mon Sep 17 00:00:00 2001
From: clover caruso <git@paperclover.net>
Date: Fri, 2 Oct 2026 12:49:27 -0700
Subject: [PATCH] fix: a box laid out inverted paints empty instead of failing
 the frame

A box with its bottom above its top failed the whole frame as an invalid
primitive ("Canvas drawing failed: InvalidPrimitive"), as the rename
field over a just-created section tab did. Such a box, or one smaller
than its inset, now paints empty.

Assisted-by: claude-opus-5.5
---
 crates/ui/src/lib.rs   | 10 ++++------
 crates/ui/src/tests.rs | 27 +++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/crates/ui/src/lib.rs b/crates/ui/src/lib.rs
index 433bc139cfc273e9d086473eabb55cb94ae579ed..d311832b75166bb07f98fd76601fb84916f0d42e 100644
--- a/crates/ui/src/lib.rs
+++ b/crates/ui/src/lib.rs
@@ -1589,12 +1589,10 @@ impl Ui {
         });
         let border = blend(node.border, node.hover_border);
         let [left, top, right, bottom] = node.inset;
-        let painted = [
-            rect[0] + left,
-            rect[1] + top,
-            rect[2] - right,
-            rect[3] - bottom,
-        ];
+        // A box squeezed smaller than its inset, or than nothing as it eases shut, paints
+        // empty rather than inverted.
+        let [x, y] = [rect[0] + left, rect[1] + top];
+        let painted = [x, y, (rect[2] - right).max(x), (rect[3] - bottom).max(y)];
         let size = [painted[2] - painted[0], painted[3] - painted[1]];
         if let Some(color) = node.shadow {
             let (own, menu);
diff --git a/crates/ui/src/tests.rs b/crates/ui/src/tests.rs
index 97f317480f7bc253eba8e4aff47b2cd2cbf40fb3..c561e4079ab66f3fc169ff4075e65095d5261d99 100644
--- a/crates/ui/src/tests.rs
+++ b/crates/ui/src/tests.rs
@@ -3127,3 +3127,30 @@ fn a_loose_dialog_fits_its_contents_to_the_window_and_its_side_stretches_to_its_
         "row 10 at {row}, the list's top at {top}"
     );
 }
+
+#[test]
+fn a_box_squeezed_past_its_inset_paints_empty_not_inverted() {
+    let mut ui = Ui::new(Theme::light(), DOUBLE_CLICK);
+    frame(&mut ui, |ui| {
+        ui.leaf(
+            "row",
+            Spec {
+                size: [px(100.0), px(4.0)],
+                fill: Some([1.0; 4]),
+                gradient: Some([0.5, 0.5, 0.5, 1.0]),
+                inset: [0.0, 0.0, 0.0, 10.0],
+                ..Spec::default()
+            },
+        );
+    });
+    let rect = ui.display.iter().find_map(|item| match item {
+        Display::Rect { rect, .. } => Some(*rect),
+        _ => None,
+    });
+    let [left, top, right, bottom] = rect.expect("the row paints");
+    assert!(
+        right >= left && bottom >= top,
+        "{:?}",
+        [left, top, right, bottom]
+    );
+}
-- 
2.54.0