Compose: allow overlapping sequences with xkbcommon

Gtk-based apps support overlapping Compose sequences, but it seems Qt-based do not, at least when using the IM backed by xkbcommon.

For instance, in the following Compose file only the sequence #3 is available:

<A> <B> <C>     : "X"  #1
<A> <B>         : "Y"  #2
<A> <B> <C> <D> : "Z"  #3
<A>             : "✨" #4

I am trying to add support for overlapping sequences in xkbcommon. I would appreciate if Qt developers could give an early feedback:

• Is this feature desirable? I would say yes, to bring feature parity with Gtk.
• Is this feature possible?
• Does the implementation in xkbcommon enable this feature in Qt?

See:

• xkbcommon bug
• xkbcommon MR

Disclaimer: I am new to the Qt platform, please be kind and patient.