When offering info, it would be useful to know what OS are you using and please supply the information as can be found under: 'Help' > 'Troubleshooting information' scroll to 'Graphics' section and paste that information.

http://kb.mozillazine.org/Performance_%28Thunderbird%29 Thunderbird uses Direct2D hardware acceleration (enabled in version 5, disabled in version 9, and then re-enabled in version 31) to improve display performance. However, it can make it much worse if you have a low end graphics system. It can be disabled by setting gfx.direct2d.disabled true and layers.acceleration.disabled true using the config editor. You can verify this by looking at the "GPU Accelerated Windows" line in the graphics section near the bottom of the screen for help -> troubleshooting information. It is set to 0 if hardware acceleration is off. If its on you should see something like 1/1 Direct3D 10. or 2/2 Direct3D 11

If you are using Linux or OS X try setting layers.prefer-opengl true instead, to see if you can use OpenGL for the hardware acceleration instead. Normally you would use Direct2D under Windows and OpenGL under OS X and Linux. Several people have reported display performance problems even with these settings disabled, unless they disable Window's Aero theme. Using the NoGlass theme doesn't seem to help, but the SilverMel theme did. One person reported that after upgrading from 24.6.0 to 31.0 the main window's fonts weren't properly aliased/smoothed and some windows had unusual tints. This was worked around by setting gfx.direct2d.disabled true

Thanks for the reply. Here is a copy of my 'Graphics' section http://pastebin.com/i1URg9cK This is when my Thunderbird hardware acceleration is disabled. I believe my graphics card is not a low end card (Radeon HD 7800, with the latest official drivers) :-)

I am on Windows 7 x64

By the way, when I turn on "User hardware acceleration when available" in TB, the 'Graphics' sections shows: GPU Accelerated Windows 1/1 OpenGL

This is the info with "Use hardware acceleration when available" http://pastebin.com/mvzYuBei

re : GPU Accelerated Windows 1/1 OpenGL

Interesting as Opengl is usually used by MAC or Linux, but you have Windows.

Tools > Options > Advanced > General tab click on 'Config Editor' button

In top search type: opengl look for this line: layers.prefer-opengl value = false

Is this set to False or true?

I'm running Windows Vista with good but older graphics than you and use:

• layers.prefer-opengl Value = false
• gfx.direct2d.disabled Value = false
• layers.acceleration.disabled Value = false.

So, I have all three set to False.

I'm running the default Thunderbird theme. In Windows : Control Panel > Personlisation > Window colour and appearance running 'Windows Vista Basic'.

Your image suggests you are using a different theme - Aero or similar. What are you using? suggest you set this to the Win7 Basic.

As far as I understand - what you are doing with these configuration flags is basically disabling hardware acceleration completely. That's a workaround, not a solution. I know that if I disable HW Acceleration via the advanced options TB works fine. Turning off Aero is also not a solution as it's working fine with all of my other software, including FF. What I want is to have it enabled and resolve the alignment issue. Strange thing - I tried loading TB on a completely new profile and it works just fine, no alignment issue. Checked out "Use hardware acceleration when available" and it's checked. Went back to my main profile, restarted TB with all add-on disabled while "Use hardware acceleration when available" is checked - same problem. Leads me to believe this is not an add-on causing this.

> What I want is to have it enabled and resolve the alignment issue

What you want is currently not possible AIUI - maybe later, but not now. It seems to me toad-hall is simply trying to understand the nuances of your situation, etc

Wayne Mery said

> What I want is to have it enabled and resolve the alignment issue What you want is currently not possible AIUI - maybe later, but not now.

I think it is possible, otherwise - why would it work just fine on a new and clean TB profile as I explained?

Regarding the layers.prefer-opengl Yes, it was set to true I just set it to false and it seems to have fixed the problem!! :-) Now my hardware acceleration is on and everything works just fine. Troubleshooting info shows now: GPU Accelerated Windows 1/1 Direct3D 11

Thank you, Toad-Hall!

Good to hear all is now sorted. Just for clarity - if someone else locates this question. re As far as I understand - what you are doing with these configuration flags is basically disabling hardware acceleration completely.

• layers.prefer-opengl Value = false
• gfx.direct2d.disabled Value = false
• layers.acceleration.disabled Value = false.

No, this switches it on, but in your case you had the preference: layers.prefer-opengl Value = true, which was incorrect for your OS.

Once the settings were corrected, everything worked as expected.