Make background transparent when exporting to image

When saving to an image or copying as image I think the background should be transparent if image format supports it. Currently it is not.

I'm not sure I understand what the problem is... could you provide an example?

I suppose when you export an image to PNG, it gives you a white background, meaning if you paste the PNG on a green page it will result in a big white square instead of nice integration of the diagram element on the coloured background ?

Yes, yes, that's how it works indeed.
Although that's not how it is implemented, exports (to a file or to the clipboard) can be viewed as screenshots of the diagram, including its background. Since there is no way to set the background to being transparent (I guess we'd have to show the screen's inner wires and chips ), the produced export doesn't have a transparent background either.

The reason the background is included in the export, is because the color of the background (although it can be changed manually) is part of the identity of the diagram. This is even more true if you use an image as background (think company logo as watermark here).