There can be times when you are messing about with open reading frames, inserting residues to change frames to try to get the perfect CDS fusion. The MacVector single sequence Editor will show those (click and hold on the “Display” toolbar button) but if you select and copy, only the DNA sequence (with any overlapping features) will be copied to the clipboard. If you need to copy a specific translation of a sequence, here’s how to do it: Select the region you are interested in, then invoke Analyze | Translation… Select the “Display text view with translation” option, set the Number of Frames to 3 or 6 and click OK.
From the resulting result window, you can select the text of the amino acid sequence you are interested in, copy, and then create a new sequence document (File | New From Clipboard) or paste into an external application.