I would lie if I said I did not ever do something similar, and I am not really aware of any court cases or litigations based on copying a design. Core functionalities, sure.
There is many an open source software that could actually use a little bit of copying from the thing they are trying to emulate. GIMP is still one of the ugliest programs I have installed on my computer.
> I am not really aware of any court cases or litigations based on copying a design
Apple tried it in the 90's with the infamous "look and feel" lawsuits against Microsoft. They lost.
They've had more success suing Samsung over phone design and UI (which was about more than "rounded corners" to be sure, but a lot of the patents are still questionable).
There is many an open source software that could actually use a little bit of copying from the thing they are trying to emulate. GIMP is still one of the ugliest programs I have installed on my computer.