Here is a simple tip to add a custom background for the Comment boxes..
Proceed as follow:
- Select a Cell/Right Click
- Select the "Insert Comment" option
- A red triangle appears at the top right of the cell
- Delete the text if you want
- Click on the hatched frame and then right click: Format Comment
- Select Color and Lines tab/Fill/Color/click on the small arrow to expand the options.
- Select the "Fill Effets Options" and in the new Window that opens Select the Texture Tab.
- Click on the "Other texture" button and select an image from your hard drive (or any other media)
- E.g: With a Custom image: