I'm doing some research about using IS as UI prototyping tool. Simple need: I want create background that will be used in many components. I found that if I scale shape as group stroke loose linking with original that break my idea. Is it bug or feature? Look at button like shape on right.

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I don't quite understand the question. Could you explain more?

In the SVG you provided, is it the large OK button on the right, that you're having trouble with? I see that the rectangle has been grouped. But the "OK" is not part of the group. So that if you select the group and scale it, the OK isn't affected, because it's not part of the group.

I also notice that there's a smaller rectangle which has a white check mark on top, and which is a clone of the rectangle above it. The large OK rectangle is not a clone, so it wasn't linked to anything.

I've grouped the clone to experiment, and it appears to stay linked to the original. I can edit the stroke on the original and the same thing happens to the clone.

That's about all I could say, until I understand better.