The main editor panel is a tabbed window which displays editors for the various script assets.
The editor panel can also display previews of icons and images.
To edit (or view) a script asset, simply double-click it in the asset panel, or use the Open command in the Assets menu (or right-click context menu). A new tab will open in the editor panel for each asset. If an asset has been modified since the script was last saved, the tab indicates this with a red dot:
The corresponding tab in the asset panel also uses a red dot to indicate that something within it has changed. You can close the tab for the modified asset without losing your changes - Opus will alert you if you try to close the whole editor while changes are unsaved.