"Insert Emoji" in typeahead-find window causes problems in Ubuntu MATE 18.04

[Stuart Langridge]

Steps to reproduce, under Ubuntu 18.04:

1. launch a Caja window
2. type a few characters in it, so that it starts doing typeahead find in this folder, in a textbox in the bottom right corner of the window
3. right-click in that textbox and say "Insert Emoji" in the popup menu that appears (under Ubuntu MATE 18.04 at least)

The system... does not like this. The pointer seems to bizarrely get locked into the Caja window, where it draws endless selection rectangles just when moving; alt-tab doesn't work; it seems impossible to focus another application. Fortunately, ctrl-alt-t to launch a Terminal works, in which one can killall caja.

I suspect this may be because the caja typeahead popup textbox is ephemeral and disappears when unfocused, and popping up the emoji chooser overlay defocuses the textbox, causing the textbox to disappear, the emoji panel to now not have any widget to point at, and everything to get confused.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: caja 1.20.2-4ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CurrentDesktop: MATE
Date: Wed May 9 15:04:53 2018
InstallationDate: Installed on 2014-04-07 (1493 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
SourcePackage: caja
UpgradeStatus: Upgraded to bionic on 2018-04-28 (11 days ago)

[Stuart Langridge (sil)]

(unsure whether this is a Caja bug, or an Ubuntu MATE bug with its emoji overlay, so adding references to both.)

[Launchpad Janitor (janitor)]

[Expired for caja (Ubuntu) because there has been no activity for 60 days.]