How does one enter Unicode characters into systems with Mir?

In X.org/X11, I could use the keyboard shortcut "Ctrl+Shift+U" in any text field and then type a Unicode character code to insert special characters. However, this does not work in Mir. What is the keyboard shortcut for inserting special characters/Unicode in Mir? I'm using Ubuntu 16.04. Also, I'm curious what the key combination is in Wayland, but more importantly I want to know about Mir.