[Lazarus] Lazarus not working on Fedora 32 beta

[C Western]

I have recently upgraded to Fedora 32 beta (though I think the packages 
are pretty close to their final versions). The Lazarus IDE misbehaves - 
in the editor all characters entered are doubled up. It is specific to 
the editor window - other dialog boxes and my applications work fine. A 
little debugging indicated that the UTF8KeyPress handler (used by 
SynEdit) is being invoked twice, though I don't entirely understand the 
logic used. This is with Lazarus trunk, though the same issue manifested 
with the Lazarus included in the Fedora repositories, so I suspect a 
recent update to glib2, or a related library.

Is anyone else seeing this, or have I been particularly ingenious in 
miss-configuring my system?

Colin