OSK disappears when focus returns to window from popup

[wmww]

To reproduce:

• open gedit inside ubuntu-frame with OSK enabled
• ctrl+s
• Save-as window appears, OSK is still there
• esc
• Save-as window (unexpectedly) closes and OSK (unexpectedly) closes
• Save-as window (expectedly) closes and OSK (unexpectedly) disappears. Clicking the gedit window does not bring it back.

On Sway the OSK does not disappear when save-as window is closed.

[RAOF]

I can't quite test this properly on my Dell 2-in-1, as the physical keyboard gets disabled when I flip it into tent mode so GNOME Shell will pop up the OSK (and, so, I can't press ).

However, this looks like expected behaviour? Hitting should close the save-as window. I suspect that gedit might also be buggy - under GNOME Shell, when hitting the “save” button the save-as dialog will pop up with the location text field focused but will have hidden the OSK. Then, when dismissing the save dialog and focusing gedit's text entry, the OSK doesn't pop up until you tap it a second time‽

I guess what I'm saying is: expect OSK handling handling to be a bit janky in (at least) GNOME apps, regardless of what Mir does.

[wmww]

I fixed my initial description to include that:

• the OSK doesn't appear, even if you tap gedit again
• this doesn't happen on Sway, indicating the problem lies in Mir

[wmww]

Problem is it's not sending a zwp_text_input_v3.enter. It's also not sending a wl_keyboard.enter, but keyboard events do get directed to the surface at which time keyboard enter is sent.

Root cause seems to be the same as #1626.