hey-bud said

You know sometimes I'll switch to the Lightning calendar tab and it paints nothing, but I'll move my mouse around and some elements will get painted like the individual calendar days. Very weird but I know that Firefox had recently fixed this exact same issue of what they identified as a "race condition" (see bugzilla #1067470) I have the "TT DeepDark" theme but I have confirmed the issue is still present on the default theme as well.

I FOUND A PARTIAL SOLUTION: looks like by just turning off HW acceleration fixes the issue for me. That's in tools ->options -> advanced and it's the last option there on the "general" tab.

Hey mods, please don't chose my own "partial solution" above as the "chosen answer." This is still an outstanding issue that hasn't been addressed yet (and I'm open to the possibility that it might only affect me for some reason.)

My guess would be that between versions 31 and 38, Thunderbird got the OMTC feature, "off main thread composition," which can suffer from the problem you describe in some cases. That does seem to be what that bug you mentioned is related to.

I don't know when it will be resolved for Thunderbird, but have you checked for updates to your graphics card/chipset driver software? This article has suggestions for safe places to look: Upgrade your graphics drivers to use hardware acceleration and WebGL

jscher2000 said

My guess would be that between versions 31 and 38, Thunderbird got the OMTC feature, "off main thread composition," which can suffer from the problem you describe in some cases. That does seem to be what that bug you mentioned is related to. I don't know when it will be resolved for Thunderbird, but have you checked for updates to your graphics card/chipset driver software? This article has suggestions for safe places to look: Upgrade your graphics drivers to use hardware acceleration and WebGL

Thanks for the reply, and yes my AMD R9 280 drivers (14.501.1003-141120a-177998C) are up to date. I *could* update to their AMD beta release (which had additional support for the video game gta5 blablabla) but I'm not really a "beta" kinda guy (due to compulsory telemetry sending of data) and would rather keep everything on the release schedule.

Also, this issue cropped up for me only upon upgrading to 38.0.1 and I use Thunderbird every day so I (most likely) had the previous release version (I'm seeing 31.7.0 on the Mozilla wiki and don't know if that's correct or not) and everything was fine then.

Btw, there's one flag I like to immediately set to false both in Thunderbird and Firefox and have no idea if it's releated (probably not but w/e) is: "media.peerconnection.enabled" - I'm not particularly interested in Mozilla revealing my external IP to any server that does a STUN lookup for WebRTC functionality.

If turning odd hardware acceleration fixes the issue for you. As far as I am concerned that is a fix. Not partial. Complete.

I am pushing to have it disabled for everyone. Instead we got an option to disable it in the User interface. I might have a different opinion if any one could give me a reason for using it. But all I can get is basically because Firefox does and they test with it on. As far as I can see in a 2d desktop environment without video it is about a useful a rain in a flood. Just causes myriad problem.

Matt said

I might have a different opinion if any one could give me a reason for using it.

An email that contains in-line vector graphics without the need to open an external firefox instance (or alternatively higher cpu utilization) to render them? Font smoothing and shadowing? Better skin support?

If the devs never intended the program to benefit from hardware acceleration in some fashion not immediately apparent, they would have greyed out the option (or for experimental purposes, left it as a flag in the config editor.) Apparently they do since I don't consider the option to be "simply a port from firefox." Remember when Mozilla removed the "disable javascript" in the general options in firefox? That example shows that they're quite fickle about what the general options should be.

Update: looks like this bug has been confirmed officially (from the same bug that affected the previous version of firefox), see the bugzilla thread: https://bugzilla.mozilla.org/show_bug.cgi?id=1067470#c296

No idea if it's being worked on though.

Update: looks this is resolved by turning OFF the gpu's overclock. Turned off mine and tabs/selecting other items are now painting like they should. Considering how little people OC their discreet gpu, I understand why this isn't a more apparent problem. I'll update this if things start to act up again.

(Delayed) Update: looks like for me this has been silently resolved with version 38.1.0, released on 9 July 2015. Initially I thought it was an OC issue with my gpu but after further testing that wasn't the case.