ULAYERS opens in a drawing without underlays; the ribbon runs ULAYERS

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/commands/display.rs

@@ -2051,7 +2051,7 @@ impl OpenCADStudio {
                 }
             }
 
-            "UNDERLAYLAYERS" | "ULAYERS" => self.open_underlay_layers_dialog(i),
+            "ULAYERS" => self.open_underlay_layers_dialog(i),
             "RECAP" | "SYNCPVIEWPORTS" => {
                 self.command_line
                     .push_info(crate::tf!("{cmd}: not yet implemented.").as_ref());

src/app/commands/pdf_dialogs.rs

@@ -289,7 +289,8 @@ impl OpenCADStudio {
         }
     }
 
-    /// ULAYERS: every underlay of the drawing, the selected one first shown.
+    /// ULAYERS: every underlay of the drawing, the selected one first shown
+    /// (none: an empty dialog).
     pub(in crate::app) fn open_underlay_layers_dialog(&mut self, i: usize) {
         let document = &self.tabs[i].scene.document;
         let selected: Vec<codec::Handle> = self.tabs[i]
@@ -329,10 +330,6 @@ impl OpenCADStudio {
                 hidden: crate::scene::model::pdf_layers::hidden_layers(u),
             });
         }
-        if targets.is_empty() {
-            self.command_line.push_error("No underlays found.");
-            return;
-        }
         let current = targets
             .iter()
             .position(|t| selected.contains(&t.handle))

src/modules/insert/underlay_layers.rs

@@ -6,6 +6,6 @@ pub fn tool() -> ToolDef {
         id: "UNDERLAYLAYERS",
         label: "Underlay\nLayers",
         icon: ICON,
-        event: ModuleEvent::Command("UNDERLAYLAYERS".to_string()),
+        event: ModuleEvent::Command("ULAYERS".to_string()),
     }
 }

src/ui/window/pdf_dialogs.rs

@@ -1037,10 +1037,16 @@ pub fn view_layers<'a>(
 ) -> Element<'a, Message> {
     let names: Vec<String> = state.targets.iter().map(|t| t.name.clone()).collect();
     let target = state.targets.get(state.current);
+    let has_underlays = !names.is_empty();
     let underlay = pick_list(target.map(|t| t.name.clone()), names, |n: &String| {
         n.clone()
-    })
-    .on_select(|n| msg(PdfDialogMsg::LayersUnderlay(n)))
+    });
+    // No underlays: the list stays empty and disabled.
+    let underlay = if has_underlays {
+        underlay.on_select(|n| msg(PdfDialogMsg::LayersUnderlay(n)))
+    } else {
+        underlay
+    }
     .text_size(12)
     .padding([5, 8])
     .width(Fill);