When using floating within a Dashboard it would be great to, when selecting 'None' for the shading of the sheet fill, have it actually be none instead of white.
A few views I have worked on recently have highlighted how difficult it is to create something different with images, as the sheet will always block the background image with a white background. None is really just white and so confusing.
You can see where I am trying to go with the Rugby viz I recently helped build and another side project I did to test how much you could do without the ability to have real transparency.
The only way to trick transparency is with an X and Y chart, with a background image that is the same as the Dashboard background.
Another way is to create transparent png images, then overlay this on the floating sheet, but this then kills the interactive element so you need to create buttons; you lose the tooltip completely in this case.
Having no transparency is a huge creative limitation.
I love that I can see and understand my data, I just would love to make it look amazing when I see it.