Fill texture and tilemap collision only where it is edited

Textures.md

@@ -90,7 +90,8 @@ then edits the selected frame's outlines instead of the frames.
 
 Corners land on whole pixels inside the frame and are stored relative to its top-left corner, so
 they move with the frame. Every step is one undo step. The outlines of all frames are always shown;
-one that crosses itself is drawn red and collides as none.
+only those of the selected frame have their area tinted, so the tint does not lie over the art of
+every other frame. One that crosses itself is drawn red and collides as none.
 
 ### Generate collision…
 

Tilemaps.md

@@ -193,7 +193,8 @@ rather than twenty. In the scene view they are outlined the way a collider is, g
 drawing; the game view does not show them. The outline runs only along the **outer edge** of all
 that blocks (#173): where two rectangles or the pieces of outlined cells meet, no stroke is drawn,
 so a wall of several rectangles or a lake of many pieces shows as one shape. Collision itself keeps
-the pieces.
+the pieces. The area is tinted only while the map is selected, and then only where the active
+layer blocks: the outline shows the whole map, the tint what the layer you paint on adds to it.
 
 A solid tile's **Friction** and **Bounciness** (#193) are what a cell of it offers, read by `Move`
 and by the physics engine like a collider's (see [Physics](Physics#the-material)). Cells of tiles