From 52438c7cea2bd1203abea40666c3348a29e8fe9b Mon Sep 17 00:00:00 2001
From: dotCooCoo <RobertLeeLW@gmail.com>
Date: Thu, 5 Nov 2026 06:11:21 -0800
Subject: [PATCH] Fix item 1747: stop hidden thumbnail panel jobs

---
 crates/ui-egui/src/panel_docking.rs       | 10 ++++++++++
 crates/ui-egui/src/panel_docking/tests.rs | 19 +++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/crates/ui-egui/src/panel_docking.rs b/crates/ui-egui/src/panel_docking.rs
index 4b9a5ad14..87f3583d0 100644
--- a/crates/ui-egui/src/panel_docking.rs
+++ b/crates/ui-egui/src/panel_docking.rs
@@ -270,6 +270,11 @@ pub(crate) fn showing(ui: &UiState, panel: &str) -> bool {
     (ui.open_panel.as_deref() == Some(panel) && iconic) || (!iconic && layout.panel_state(&panel.to_string()) == craft_ui::docking::PanelState::Front)
 }
 
+/// Can either panel that uses row thumbnails be seen, including in a floating window or flyout?
+fn thumbnail_panel_showing(ui: &UiState) -> bool {
+    ui.dock && ui.screen_mode < 3 && (showing(ui, "layers") || showing(ui, "links"))
+}
+
 /// Where a panel with no other destination goes: a panel of the first expanded dock column,
 /// else of any column.
 fn first_dock_panel(layout: &Layout<String>, except: &str) -> Option<String> {
@@ -1173,6 +1178,11 @@ pub(crate) fn show(app: &mut VectorcraftApp, ui: &mut egui::Ui) {
         app.open_dropped_files(window.dropped, None, shift);
     }
     forward_keys(app, &ctx, output.forwarded_events, output.forwarded_modifiers);
+    if !thumbnail_panel_showing(&app.ui) {
+        // No panel can ask for these rows again this pass. Keep the cache of open documents, but
+        // discard worker jobs queued behind the one already rendering.
+        crate::panels::layers::show_thumbs_of(None);
+    }
 }
 
 /// Whether a modal is open: a dialog, About, the command palette, a native file dialog, or a
diff --git a/crates/ui-egui/src/panel_docking/tests.rs b/crates/ui-egui/src/panel_docking/tests.rs
index f8287944b..3afb41f96 100644
--- a/crates/ui-egui/src/panel_docking/tests.rs
+++ b/crates/ui-egui/src/panel_docking/tests.rs
@@ -161,6 +161,25 @@ fn a_tab_dragged_out_floats_and_comes_back_where_it_was_after_its_window_closes(
     assert!(h.tab("layers").is_some());
 }
 
+#[test]
+fn thumbnail_work_is_needed_only_while_layers_or_links_can_be_seen() {
+    let mut h = Harness::new();
+    h.app.run("window.panel", json!({"panel": "layers"})).unwrap();
+    assert!(thumbnail_panel_showing(&h.app.ui));
+    h.app.ui.dock = false;
+    assert!(!thumbnail_panel_showing(&h.app.ui), "Tab hides every panel");
+    h.app.ui.dock = true;
+    h.app.ui.screen_mode = 3;
+    assert!(!thumbnail_panel_showing(&h.app.ui), "presentation mode hides panels");
+    h.app.ui.screen_mode = 0;
+    h.app.run("window.panel.float", json!({"panel": "layers"})).unwrap();
+    assert!(thumbnail_panel_showing(&h.app.ui), "a floating Layers panel still needs thumbnails");
+    h.app.run("window.panel", json!({"panel": "layers", "toggle": true})).unwrap();
+    assert!(!thumbnail_panel_showing(&h.app.ui));
+    h.app.run("window.panel", json!({"panel": "links"})).unwrap();
+    assert!(thumbnail_panel_showing(&h.app.ui), "the Links flyout also uses row thumbnails");
+}
+
 /// A Character field shortcut with the Character panel in front of its floating window brings
 /// that window forward and leaves the panel showing.
 #[test]