Under Linux, the workaround is to read the keyboard configuration in /usr/lib/kbd/keymaps (location may vary with distribution) ot to use an on-screen keyboard.

The best I’ve ever seen ships with MacOS: it displays the keyboard on screen and updates when you press modifier keys. There are various OS utilities allowing you to discover what you can generate. It is not convenient to change keyboard layout through system software because you always look at the physical keyboard when you need an uncommon character (unless you affix small stickers on key side) even when you know where it is supposed to be with the alternate keyboard. Their location is often OS-specific and may have various locations when variants are offered. When dead key is not a primary key (one with the diacritic marked on top), it is not always obvious to find them. keys which do not generate characters by themselves but add a diacritic on the next character.

Since you’re asking specifically for French, I assume you aren’t a French user because, in this case, you would use “dead keys”, i.e. That matter is not LibO -specific, it is rather an OS issue (which is yours?)

E with an accent mark french