Hello,

I try to increase the font size of the Tinymce4 source code dialog box.(back-end)
I have had a look to this page
and to that one

The admin editor does use my config according to those pages (font size is larger in my Tinymce editor window), but the text in the source code box is unchanged.
Does someone knows what should be done ?
Thanks in advance.

Yes, the custom CSS way our docs describe are for the formatted editor view and not the source code view. It might be possible but you might need to find out the classes tinyMCe adds and add defines for those to the custom content_css file.

Problem solved : I've added
font-size: 18px;
to
.mce-textbox.mce-multiline {
padding: 4px;
height: auto;

}
in the file skin.min.css

i know this is not the right way because on next update, my setting will be erased, but it does work.

Haven't you tried doing this via the custom.css file? I have not tried but I believe that should work as well, perhaps with an !important.

Otherwise you can also create your own skin and a custom config file using it to avoid overwriting.