right click to copy text does not work

[Christo]

Reproduce:
Open Thunderbird ----> In folder pane, select appropriate folder ----> Select any message from thread pane ----> view message in message pane.
From message pane select any word or words ----> right click to select. Right click menu is displayed for a fraction of a second, and then auto selects the "Print..." option.

Cannot make any other selections.

Workaround:
Double click on e-mail in thread pane ----> opens in new window.
Then select word or words, right click and you can now select a different option.

Thunderbird version: 68.4.1 (64-bit)
Running: Kubuntu 18.04.4 LTS
KDE Plasma version: 5.12.9
KDE Frameworks version: 5.44.0
QT version: 5.9.5
Kernel: 5.3.0-42-generic

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: thunderbird 1:68.4.1+build1-0ubuntu0.18.04.1
ProcVersionSignature: Ubuntu 5.3.0-42.34~18.04.1-generic 5.3.18
Uname: Linux 5.3.0-42-generic x86_64
AddonCompatCheckDisabled: False
ApportVersion: 2.20.9-0ubuntu7.12
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: christol 1855 F.... pulseaudio
BuildID: 20200110142707
Channel: Unavailable
CurrentDesktop: KDE
Date: Mon Mar 23 08:52:13 2020
Extensions: extensions.sqlite corrupt or missing
ForcedLayersAccel: False
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
IncompatibleExtensions: Unavailable (corrupt or non-existant compatibility.ini or extensions.sqlite)
InstallationDate: Installed on 2019-08-16 (219 days ago)
InstallationMedia: Kubuntu 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
IpRoute:
 default via 192.168.2.251 dev wlo1 proto dhcp metric 600
 169.254.0.0/16 dev wlo1 scope link metric 1000
 192.168.2.0/24 dev wlo1 proto kernel scope link src 192.168.2.103 metric 600
Locales: extensions.sqlite corrupt or missing
MostRecentCrashID: bp-d6befb62-deb5-49f0-ad18-eabd10200311
PrefErrors: Unexpected character ',' before close parenthesis @ /usr/lib/thunderbird/omni.ja:greprefs.js:1141
PrefSources: prefs.js
Profiles: Profile0 (Default) - LastVersion=68.4.1/20200110142707 (In use)
RunningIncompatibleAddons: False
SourcePackage: thunderbird
Themes: extensions.sqlite corrupt or missing
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/17/2019
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.1.8
dmi.board.name: 0M14W7
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr1.1.8:bd04/17/2019:svnDellInc.:pnLatitude5500:pvr:rvnDellInc.:rn0M14W7:rvrA00:cvnDellInc.:ct10:cvr:
dmi.product.family: Latitude
dmi.product.name: Latitude 5500
dmi.product.sku: 08B9
dmi.sys.vendor: Dell Inc.