Keyboard combination keys not respected on Ubuntu/Linux/KDE

I’m using a keyboard layout that uses dead key combinations to produce extended characters (US, international AltGr combining). These combinations don’t work in LibreOffice (tried Writer, Calc, Draw).

That is, if I type AltGr+:+a I get an ä everywhere but LibreOffice. In LibreOffice no character is produced.

How can I get LibreOffice to use my keyboard layout?

Which is your locale? Is AltGr+: a standard dead key in the layout?

What is the version of KDE Plasma? Eventually of Qt?

Have you customised the keyboard rules?

LO doesn’t use the AltGr modifier for its keyboard shortcuts, so it shouldn’t be intercepted.

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This appears to be an issue with LibreOffice 6.0 and support for Unicode keyboard input. I’ve upgraded to the 7.0 series and the keyboard works as expected.