Copy-Paste option in GUI

Someone in my group was asking for a 'Copy-Paste' functionality in the GUI, which indeed seems very convenient in certain situations. I have a vague memory that the GUI used to have this, but in any case the current version doesn't allow this (as far as I can see).

Adding this turned out to be not too difficult, but as I'm not used to dealing with the GUI, it would be great if you could check whether these changes are appropriate and whether it behaves intuitively. At least it works as currently intended:

Now, in the 'Add atoms' window there is the option to copy-paste the currently selected atoms ('off' by default). Clicking 'Add' then copy-pastes them, by default right on top of the previously selected atoms. So the user will need to either un-tick the 'Check positions' box or change the (0,0,0) coordinates in the window. Like usual when adding new atoms, those atoms are automatically selected and can then be moved away into the desired location.