Tabs: Above Text checks the place below text against the window's top

The place below the text was taken even when the text was panned above
the canvas, which put the panel above the main window. It is now taken
only when it is at or below the window's top. A docked Tabs panel is
measured at the 360-point height it floats at, not 240, so it is placed
below the text only when it fits there.

crates/ui-egui/src/panel_docking.rs

@@ -1237,7 +1237,7 @@ const DOCK_LABELS: &[(&str, &str)] = &[
 ];
 
 /// The size a panel floats at (tab strip included), whatever the size of the dock it left.
-fn floating_size(panel: &str) -> egui::Vec2 {
+pub(crate) fn floating_size(panel: &str) -> egui::Vec2 {
     match panel {
         "properties" | "layers" | "libraries" => egui::vec2(300.0, 420.0),
         // Tall enough to show its Corners and Shared Edges sections, last in it, which the Corner

crates/ui-egui/src/panels/tabs.rs

@@ -264,15 +264,19 @@ fn above_text(app: &mut VectorcraftApp, ctx: &egui::Context, n: &Node, span: f64
         return None;
     }
     let width = span as f32 * per + RULER_LEFT * 2.0;
-    let height = crate::panel_docking::layout_of(&app.ui).floating.iter().find(|w| w.contains(&"tabs".to_string())).map_or(240.0, |w| w.rect[3]);
-    // Text near the top of the window: the panel goes just below the text when it fits there in
-    // the canvas, else at the window's top, so its bar stays where it can be grabbed rather than
-    // above the screen.
+    let height = crate::panel_docking::layout_of(&app.ui)
+        .floating
+        .iter()
+        .find(|w| w.contains(&"tabs".to_string()))
+        .map_or(crate::panel_docking::floating_size("tabs").y, |w| w.rect[3]);
+    // Text near the top of the window: the panel goes just below the text when that place is in
+    // the window and the panel fits there in the canvas, else at the window's top, so its bar
+    // stays where it can be grabbed rather than above the screen.
     let above = on_screen.top() - height - 6.0;
     let below = on_screen.bottom() + 6.0;
     let top = if above >= 0.0 {
         above
-    } else if below + height <= app.canvas_rect.map_or(f32::NEG_INFINITY, |c| c.bottom()) {
+    } else if below >= 0.0 && below + height <= app.canvas_rect.map_or(f32::NEG_INFINITY, |c| c.bottom()) {
         below
     } else {
         0.0

crates/ui-egui/src/panels/tabs/tests.rs

@@ -1081,3 +1081,28 @@ fn above_text_keeps_the_panel_bar_in_the_window() {
         assert_eq!(g.native.unwrap()[1], 100.0 + top, "text {text_height} high: the OS window");
     }
 }
+
+/// Position Panel Above Text puts the panel at the window's top when the place below the text is
+/// above the window (text panned above the canvas), or when the panel at the height it floats at
+/// does not fit below the text in the canvas.
+#[test]
+fn above_text_puts_the_panel_at_the_top_when_below_the_text_does_not_fit() {
+    // The view's centre and the text's height: panned so the text is above the canvas, and a text
+    // whose bottom leaves room for 240 points of panel but not for the 360 it floats at.
+    for (center_y, text_height) in [(600.0, 100.0), (350.0, 340.0)] {
+        let mut app = VectorcraftApp::new(Session::new(), Default::default());
+        app.session.execute("file.new", &json!({"width": 600, "height": 800})).unwrap();
+        app.session.execute("text.create", &json!({"x": 40, "y": 20, "text": "a	b", "area": {"width": 300, "height": text_height}})).unwrap();
+        app.canvas_rect = Some(egui::Rect::from_min_size(egui::pos2(50.0, 40.0), vec2(1000.0, 700.0)));
+        if let Some(v) = app.view_mut() {
+            v.zoom = 1.0;
+            v.center = vectorcraft_geom::Point::new(300.0, center_y);
+        }
+        let (node, _, span) = current(&app).unwrap();
+        let ctx = egui::Context::default();
+        above_text(&mut app, &ctx, &node, span).unwrap();
+        let layout = app.ui.docking.clone().unwrap();
+        let g = layout.floating.iter().find(|w| w.contains(&"tabs".to_string())).unwrap();
+        assert_eq!(g.rect[1], 0.0, "view centered at y {center_y}");
+    }
+}