editor: game running badge and stop game button during play-tests, crosshair for play from camera position while shift is held, readable outliner names, plain error dialogs with details and no stuck loading status, inspector hints wrap with the dock

docs/manual/03-editor-window.md

@@ -11,7 +11,7 @@ The window has six areas:
 | **Options bar** | Above the viewport: the active tool with its options, then **Snap**, the move step, the angle step, **World / Local**, the camera view and **Layers**. |
 | **Viewport** | The level in 3D. See [Navigating the viewport](04-navigation.md). |
 | **Panels** | Docked around the viewport: Outliner, Objects, Environment, History on the left, Inspector and Visibility on the right, Assets, Textures and Problems at the bottom. |
-| **Status bar** | Messages, the item under the mouse pointer, the cursor position in cells and the grid cell, counts (tiles · objects · waypoints · selected), the result of the last build (click it to open Problems) and the progress of background work. |
+| **Status bar** | Messages (and a green **Game running** badge during a play-test), the item under the mouse pointer, the cursor position in cells and the grid cell, counts (tiles · objects · waypoints · selected), the result of the last build (click it to open Problems) and the progress of background work. |
 
 ## The start page
 
@@ -68,6 +68,10 @@ top), **Objects** (by category and type), **Waypoint chains**, **Zones**, **Ligh
 **Brushes** and **Assets** (tile models, imported meshes, texture pages). The filter field finds
 items by name, type or id.
 
+Several items of the same kind are numbered in level order – *Coin 1*, *Coin 2*, *Floor 1*,
+*Floor 2* – and the grey column on the right shows where they are (position in cells, for tiles
+the height). Hover a row to see its internal id (e.g. `brush:n19`), which problem messages use.
+
 * Click selects, **Shift+click** and **Ctrl+click** add to the selection, double-click frames
   the item in the viewport.
 * The eye button on a row shows or hides the item in the viewport.