Added note on sprite trimming and slice-9

docs/en/manuals/atlas.md

@@ -81,7 +81,7 @@ Size
 : The width and height of the image (read-only).
 
 Sprite Trim Mode
-: How the sprite is rendered. The default is to render the sprite as a rectangle (Sprite Trim Mode set to Off). If the sprite contains a lot of transparent pixels it may be more efficient to render the sprite as a non rectangular shape using between 4 and 8 vertices.
+: How the sprite is rendered. The default is to render the sprite as a rectangle (Sprite Trim Mode set to Off). If the sprite contains a lot of transparent pixels it may be more efficient to render the sprite as a non rectangular shape using between 4 and 8 vertices. Note that sprite trimming does not work together with slice-9 sprites.
 
 Image
 : Path to the image itself.

docs/en/shared/slice-9-texturing.md

@@ -28,6 +28,10 @@ The *Slice9* texture scaling described above is only applied when you change box
 If you change scale parameter of the box node or sprite (or on the game object) - the node or sprite and texture is scaled without applying *Slice9* parameters.
 :::
 
+::: important
+When using slice-9 texturing on Sprites the [Sprite Trim Mode of the image](https://defold.com/manuals/atlas/#image-properties) must be set to Off.
+:::
+
 
 ### Mipmaps and slice-9
 Due to the way mipmapping works in the renderer, scaling of texture segments can sometimes exhibit artifacts. This happens when you _scale down_ segments below the original texture size. The renderer then selects a lower resolution mipmap for the segment, resulting in visual artifacts.