Make wallpaper interactive
First, this is not another "attach a wallpaper to a thought" duplicate.
Sometimes, you have to remember of something and an illustration is much more meaningful than a line of text.
My idea is to make the background of PB interactive. Allow us to lock/unlock the background to place and size images, the way wich is more relevant for our mind.
So, we obtain a "mosaic" background with fixed images thoughts under the flow of classical texts thoughts (remember the html background option with active desktop under windows). This is even more coherent with a custom canvas if the background can follow the canvas movements.