The Csound score editor (or Csound composition editor) is very similar to the musical phrase editor (see Musical phrase editor).
It is always linked to a specific CSD file, which is why you can not create a new one from the "Widgets" menu. Instead, use the "Edit score in widget" from the "CSD -> Surmulot" submenu.
The main difference between the musical phrase editor and the score editor comes from the arbitrary format of score i-statements. Apart from the first three there is no meaning associated to the p-fields. For example there is no generic way to know which p-field is responsible for the pitch or the volume of the csound note described by the i-statement; and we must take into account the fact that some notes do not have either pitch or volume, plus the fact that some i-statements do not describe a note at all.
To enable editing in a meaningful way, each Csound orchestra has to be associated to a description of its score format. The score editor allows this format to be entered interactively via context menu items; the score format can also be encoded directly as specific comments in a CSD file, in which case the editor will read it automatically. Both approaches are described below.