Highlight used fields in edit window

Often I am having to type in a reference manually (as opposed to downloading/importing one). It would be great if the fields used for the formatted reference could be highlighted somehow (either as a block colour or a an icon on the left or something similar) so that I know which fields will show up in that reference type using the output style i have chosen in my formatted bibliography

This process would be further facilitated by a preview pane in the edit window. For that matter, it would also be handy to know what the in-text citation would look like, perhaps a double-barrel previw pane?