problem

When clicking on Cur. seg. -> "Copy content from the source to target" the Cur. seg menu does not disappear so it seems like nothing happens and user clicks on that again and again and each time source is inserted into target.

addition

When you are in a segments "Source text editable", you also have enabled "Cur. seg. -> Copy content from the source to target". And when you do so.. nothing happens. Which is correct but.. well "un-expected"

solution

Add menu autoclose on clicking the "Copy content from the source to target"

addition

Disable "Copy content from the source to target" when in field "Source text editable" (and maybe other function that do not make sense here.)