Since November 2018 the RedNotebook 2.8 with the major improvement form Windows OS is available on the project page ( https://rednotebook.sourceforge.io/ ).
The internal previews are working again (before you had to view your notes using a browser, eg. Firefox).
Is there any chance to update the currently available RedNotebook Portable app from 2.6.1 to 2.8?
== 2.8 (2018-11-15) ==
* Support internal previews on Windows again (#369).
== 2.7.1 (2018-11-13) ==
* Never let search phrases end up in the main text field (fixes #401).
* Fix spell checking (fixes #412).
== 2.7 (2018-11-06) ==
* Use GtkSourceView for editor to obtain better undo/redo functionality (thanks @takluyver).
* When saving, update the list of tags in the auto-complete list for the search.
* Fix opening RedNotebook homepage from About dialog (#411).
== 2.6.1 (2018-08-21) ==
* Fix bug preventing new installations from starting up.
[Thread closed by request of OP - mod GC]