Update: when I inspect the WndProc messages that come through $"{m.Msg} {m.WParam} {m.LParam}", I note these (mostly tangential, but I’d like to document them):
Pressing ‘normal’ keys (e.g. a-z, arrows, 0-9, punctuation) does not send a message to the ElementHostEx, but instead (after I turned the volume up on my laptop), it somehow triggers a bell sound.
Mouse click comes through with 528 513 36634781 and 33 723656 33619969
Switching to another program sends 8 0 0, and switching back to NPP sends 1024 0 0
Pasting into the TextBox works, but does not trigger any messages. Similarly for copying, deleting and backspacing.
Opening the WPF About window sent 8 1116900 0
I’d like to convert the msg id to a string, I’m not familiar with their values. But there still aren’t that many messages, so perhaps I haven’t set up the dock panel correctly. I’ll try the same thing in the existing Forms version and see what comes up for comparison.