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

docs/manual/tutorial-parkour.md

@@ -69,7 +69,8 @@ plane shows as material 30. Look for:
 
 The llama should not have to start over after every fall.
 
-1. Open the **Objects** panel (left dock) and click **Checkpoint** in **Quick setups**.
+1. Open the **Objects** tab in the left dock – the ⊙ icon right next to *Outliner* (inactive tabs show only
+   their icon) and click **Checkpoint** in **Quick setups**.
 2. Click on a platform in the middle of the course.
 
 You get a checkpoint post with its respawn point just in front of it. Falling after passing it