Is there a free software for manual sequence annotation?
You might find some success with using WebApollo or JBrowse

WebApollo allows you to perform many manual annotation functions for your genes, such as editing exon boundaries, fixing coding sequences, and merging or splitting gene predictions, which looks like what might have been done in the UCA-At2g42245. It can also be used for adding various attributes, GO terms, pubmed info, or generic attributes. WebApollo actually uses JBrowse, but JBrowse itself has very flexible options for displaying annotations. The part about highlighting the alpha helix/beta sheets is not built in, but JBrowse can be configured to do lots of different renderings, and I could provide more details if you are interested. Disclaimer: I'm a WebApollo developer/JBrowse contributor.