The @theia/editor-preview extension contributes the preview editor which supports the same functionality as a regular editor widget with the exception:
if a preview editor has not "transitioned to a permanent editor" at the time an additional request to
preview a file is received, instead of opening a new editor, it will display the contents of the
newly requested file.
Events that will transition the preview to a permanent editor are as follows:
Modifying file contents being previewed
Double clicking the preview tab
Performing a drag/drop operation of the editor preview tab resulting in the tab being moved.
Issuing a request to open the file being previewed (e.g. double clicking the file in the
navigator)
The preview editor is enabled by default when the extension is included in a Theia application, but
may be disabled by modifying the preference:
editor.enablePreview
In addition to this value, the preference:
list.openMode
must be set to "singleClick" to enable opening files in preview mode.