Whenever you have information copied to the clipboard, you can choose File | New From Clipboard and MacVector will interpret any data on the clipboard and create a new document of the appropriate type. While this is most commonly used for DNA and Protein sequence documents, this also works for multiple sequence alignments and data from restriction enzyme, primer and subsequence files.
The function is particularly useful if you are using a web browser and stumble on a sequence that you would like to open in MacVector. Most web sites (e.g. Entrez and various genome browsers) have an option to view the sequence in GenBank format;
The trick here is to select from immediately before the LOCUS text at the very beginning of the sequence and include everything up to and including the two // at the end of the sequence. Copy that text and then File | New From Clipboard will not only create a new document with the sequence residues, but will also include all of the features and annotations. This also works with EMBL formatted sequence text and also simpler formats such as fasta, although in those cases no features are present in the data.
Note that File | New From Clipboard has far more functionality than simply being a shortcut to File | New followed by Edit | Paste. Firstly, it automatically accounts for the type of the data on the clipboard and creates the appropriate document. Secondly, for sequence data, it can parse out any feature information contained in formatted text on the clipboard – a straight-forward Edit | Paste will handle feature data copied from MacVector sequence windows, but not from external formatted text.