feat(layers): add non-printing layer support

src/app/mod.rs

@@ -2013,6 +2013,7 @@ pub enum Message {
     LayerToggleVisible(usize),
     LayerToggleLock(usize),
     LayerToggleFreeze(usize),
+    LayerTogglePlot(usize),
     /// Sort the Layer Manager table by a clicked column header.
     LayerSort(crate::ui::window::layers::LayerSortCol),
     /// Toggle per-viewport freeze: (layer_index, vp_col_index)