There are two ways of editing an asset:

While an asset is being edited by a third-party application, the "Edit file" dialog is shown by HelpNDoc.

To edit an asset:

Note: the asset is not yet saved to disk, the template needs to be saved from the template editor dialog.

To cancel an asset edition, click "Cancel Editing" in the "Edit file" dialog. Even if the asset file has been edited and saved using a third party editor, it won't be updated in the template.