toolbar block icons centred in their 16px box (test for all icons), tutorials say where the objects tab is

docs/manual/tutorial-first-level.md

@@ -40,8 +40,9 @@ Every change can be undone with **Ctrl+Z**.
 
 ## Step 4: A coin trail
 
-1. Open the **Objects** panel (left) and click **Coin line** under the quick setups – or press
-   **O** for the **Coin line / arc** tool.
+1. Open the **Objects** tab in the left dock – the ⊙ icon right next to *Outliner* (inactive tabs show only
+   their icon) and click **Coin line** under **Quick setups** – or press **O** for the
+   **Coin line / arc** tool.
 2. Click once at the start of the trail and once at its end. Coins appear every *spacing* cells
    on the ground (also up the ramp).