I use 4.1.4 on Ubuntu
I only had View / Print Layout, Web Layout when viewing an HTML file.
Then I played around with the LO Writer and Writer/Web options, plus the Internet options.
After I added the "browser plug-in optional check-box, the page now had View/HTML_Source.
I did not save the HTML file, since I did not want any changes to the web page.
Now that HTML file opens and always shows the View HTML_source, but then opening a second HTML file along with the first one, afer I unchecked everything I thought I changed, it opens without the HTML_Source option. Two files opened at the same time and one has the View HTML_Source and the other does not.
SO, why is one now showing that HTML source option and the other does not. The HTML_Source one did not originally have that option till I did some check-box adding. So something changed to see the HTML source code in Writer for the original and not for the next one.
YES, it is weird.
Well, now I just opened the first file and it is no longer showing the HTML_Source view option. Weirder yet.
It might have something to do with the "Field Code" check-box in Writer/Web, and the Internet / Browser Plug-in / Display documents in browser check-box. Right now, I have the field code check-box checked in Writer, but not in Writer/Web.
So do you have the Field Code check-boxes checked in one or both Writer/Web view and Writer view options, and the browser plug-in checked?
Why you see the view source option for one file and then not for another is a mystery. Was there some "script" tagged with the original file for a bit so it would show the HTML source view but not tagged with the other file. Then get "untagged" with the first one after playing around again with the check-boxes during the viewing of the file, so the LO shut down and then opening the first page again after restarting LO.
SO, this source viewing and non source viewing of the HTML files/pages is in Ubuntu's 4.1.4 [64-bit] version and not just in 4.2.0.4.
ALSO, it seems to open differently with how the page is opened. Close all your LO documents. This will display the option showing Text Document, Spreadsheet, Presentation, etc.. Also it shows the "Open" option. I just found out that if I press the "Text Document" option to open the HTML file, it does not show the HTML Source viewing option. Yet, if I open the same file using the "Open" option, instead of the "Text Document" option, I get to see the HTML Source viewing option.
So how are you opening your files? Open Text Documents? Or, just the "Open" option? It does seem to make a difference in 4.1.4.2. It may have the same affect in 4.2.0.4.
[hopefully you are not confused by my descriptions, since it is about 3:30 in the morning here. Got up to see the snow storm that hit here a few hours ago and now predicted to be in full force.]