Theming doesn't support background images with spaces in their names #9674
*When creating a custom theme and referencing background images with a space in their name, these images are not shown.
The problem is in qx.bom.element.Background.js, that doesn't take spaces in image urls into account:
So only for base64 urls the url is quoted. But this quoting also needs to be done when the url contains a space.
So my suggestion is to remove the check for base64encoding and always include the quotes.
I will supply a pull request for this.