Thanks for confirming this still an issue with the latest Thunderbird release in Ubuntu 18.04.
https://support.mozilla.org/en-US/kb/archived-messages recommends not archiving more that 2000 messages at a time but doesn't say what might happen if you do. This issue is worth reporting upstream to Mozilla (I haven't found anything relevant there yet). Your original report just said "large numbers of messages". Approximately how many? -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to thunderbird in Ubuntu. https://bugs.launchpad.net/bugs/1387439 Title: achiving large numbers of messages is slow and leaves context menu on- screen Status in thunderbird package in Ubuntu: New Bug description: Hi there When achiving large numbers of messages from my Inbox, Thunderbird leaves the context menu on-screen as an artifact. It's very annoying because thunderbird won't respond, but the context menu still stays in front of other windows when I switch to another program, eg LibreOffice as shown in the attached screenshot. Perhaps this is a problem with Unity (I am using Unity 2D here), but more likely I think it is a problem with Mozilla running this archive operation in an inefficient 'foreground' way, when really it should be a nicely backgrounded task (eg using the Activity Manager). Cheers JP --- ProblemType: Bug AddonCompatCheckDisabled: False ApportVersion: 2.20.9-0ubuntu7.4 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: john 1576 F.... pulseaudio BuildID: 20181010142617 Channel: Unavailable CurrentDesktop: Unity:Unity7:ubuntu DistroRelease: Ubuntu 18.04 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 2018-08-04 (115 days ago) InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426) IpRoute: default via 192.168.1.1 dev wlp3s0 proto dhcp metric 600 169.254.0.0/16 dev wlp3s0 scope link metric 1000 192.168.1.0/24 dev wlp3s0 proto kernel scope link src 192.168.1.9 metric 600 Locales: extensions.sqlite corrupt or missing Package: thunderbird 1:60.2.1+build1-0ubuntu0.18.04.2 PackageArchitecture: amd64 PrefSources: prefs.js ProcVersionSignature: Ubuntu 4.15.0-39.42-generic 4.15.18 Profiles: Profile0 (Default) - LastVersion=60.2.1/20181010142617 (In use) RunningIncompatibleAddons: False Tags: bionic Themes: extensions.sqlite corrupt or missing Uname: Linux 4.15.0-39-generic x86_64 UpgradeStatus: No upgrade log present (probably fresh install) UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo _MarkForUpload: True dmi.bios.date: 07/23/2013 dmi.bios.vendor: LENOVO dmi.bios.version: 8MET70WW (1.70 ) dmi.board.asset.tag: Not Available dmi.board.name: 129123M dmi.board.vendor: LENOVO dmi.board.version: Not Available dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: Not Available dmi.modalias: dmi:bvnLENOVO:bvr8MET70WW(1.70):bd07/23/2013:svnLENOVO:pn129123M:pvrThinkPadX1:rvnLENOVO:rn129123M:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable: dmi.product.family: ThinkPad X1 dmi.product.name: 129123M dmi.product.version: ThinkPad X1 dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/thunderbird/+bug/1387439/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp

