I'm using the portable version, and trying to get an external PDF viewer to be used, instead of the built in version.
I can set the PDF choice to a specific viewer or the system default.(although if I then want to change it the Preferences don't list the option again!, so resort to About:config).

The difficulty I'm having is that if I run things on the main C: drive, the alternate PDF viewer is used, but if I transfer all the files and software onto a USB drive, the internal viewer is used, irrespective of the configuration setting of 'user_pref("plugin.disable_full_page_plugin_for_types", "application/pdf");' in prefs.js.

I cannot find a way around the problem - help appreciated.

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Canada
I'm using the portable version, and trying to get an external PDF viewer to be used, instead of the built in version.
I can set the PDF choice to a specific viewer or the system default.(although if I then want to change it the Preferences don't list the option again!, so resort to About:config).

The difficulty I'm having is that if I run things on the main C: drive, the alternate PDF viewer is used, but if I transfer all the files and software onto a USB drive, the internal viewer is used, irrespective of the configuration setting of 'user_pref("plugin.disable_full_page_plugin_for_types", "application/pdf");' in prefs.js.

I cannot find a way around the problem - help appreciated.

Update:
I've found the cause, although it still leaves me with a problem. It seems that K-Meleon, or perhaps the internal PDF viewer, opens a browser window and looks for the target PDF file. If the file doesn't exist (at the point it looks), it reports the file as missing using the open window. If the PDF exists, it closes the window and then refers the file to the external PDF viewer. It doesn't allow the external viewer to act on the missing file, which is the action that I want.

I don't know what the point of opening a window, checking file exists, and closing the window is, before initiating the external viewer. Not very slick.

Because that is not the way K-meleon behaves?

First of all, what is "portable version"? Downloaded from here, downloaded elsewhere? What exact version? 7-zip? Portable Apps?

AFAIK, K-meleon doesn't have, and never had (even at times before the JSPDF had a bug when it was included with Firefox Gecko engine), a built-in pdf viewer. Or I can't recall it. As much, embedded them if there was a plugin available from the PDF reader preferred by the user, if it had one. In that case, it will depend on that specific plugin behaviour.



The default behaviour, out of the box, is to download it through the download dialog where, if you choose to open, it will be opened with the preferred reader.



Edited 1 time(s). Last edit at 05/29/2021 08:20PM by JohnHell.

I keep forgetting that stuff, being stuck on old KM version anyway and using it always with fix paths.
But if you have KM76.x, then would try if that pref helps anything:
pdfjs.disabled = true (?)

Another place I'd look around, in URL "about:preferences" and filetypes/mimetypes...
Or if that's not there, start in "about:about"....

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siria
pdfjs.disabled = true (?)

It is already by default.

And still, K-meleon doesn't ship a PDF JS built-in reader.