Originally Posted by meme
I forgot to mention there is an alternative to split view that is actually quite powerful. Its not useful for everything, but if all you want to do is edit your code manually and see the results in the Book View while still showing your code then you can try it.
Right click on the file you want to edit, and select Open With. You can then choose an external application to edit the file. You can leave the Book View version of the file displayed in Sigil, and edit the HTML code in your external text editor/HTML editor. When you save your edits in the external application, Sigil will update the file. Remember to close the file in the external application before editing the file in Sigil again or you will lose data.
This also applies to images (right click on the image in Book Browser, or on the image as its displayed in Book View or on the image's tab).
And it applies to CSS files. So you can change your CSS and see the results of your style changes immediately without having to change tabs in Sigil (although since cursor positions and style updates are now working properly its just as easy to do this in Sigil).
Gentlemen, this may be the greatest step forward in the use of Sigil.