I have created QWidget, resources and set the prefix as /files and add one image,
then in StyleSheet Editor I set

Qt Code: 
  1. background-image: url(:/files/m_bottom.png)
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the background should be seen - it's not, so I used absolute path by what I have avoided resources:
Qt Code: 
  1. background-image: url(/root/Desktop/files/m_bottom.png);
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this way the background is displayed

the same issue under Windows - but much worse, I can't set any path which makes Designer to display the image, but it's fine during run-time.

That forced me to use Designer under X11 - still the half expected not working as should