Do you have the option to activate/ have focus on the window which the mouse is hovering over? I'm thinking that if you have this option selected then the main TB window may stay in focus because that is where the mouse pointer is pointing?

If you click on 'Write' and you see the Write icon in bottom Task Bar, this sounds like the window has opened but it is either: Not got focus, so it is hidden behind the main thunderbird interface or another opened window. or it has opened in minimised state, so is not behind other opened windows.

First test: Click on Write to open a new Write message. Minimise Thunderbird, so it shows as icon on bottom Task Bar. Can you see the open Write window? If yes, then the Write message window is not getting focus.

If no click on the Write icon in the Task Bar does it then open? If yes, then the Write window is opening in a minimised state.

When you right click on the Write window icon in the bottom task bar, please list all options available - not the greyed out ones.

What results did you get?

Second Test: Restart Thunderbird in Safe mode.

Help > Restart with Addons disabled

Now test: click on Write - did Write window open in the front in focus.

If yes then it is likely that an addon is causing a conflict.

You would need to test by gradually enabling addons/extensions until you find the one which is causing the problem. So, restart thunderbird, then go to Tools > Addons disable all the addons and then enable one at a time to see when the error occurs. This will tell you which Addon is causing the problem.

Maybe the addon needs updating.

Please report back on results.

In both thunderbird Safe mode and normal mode, does Ctrl+N open a new Write window in focus ?

OK, I restarted TB in safe mode and everything works like it should. Restarted it in regular mode and doesn't work. Checked my add-ons and there are none installed. I do have several plug-ins. Could one of these be the culprit?

When you run in safe mode, it disables, 'Extensions', 'Appearance - Themes' and Dictionaries. But the various plugins are not disabled.

Safe Mode temporarily affects the following:

• All extensions are disabled.
• The default theme is used, without a persona.
• The Just-in-time (JIT) JavaScript compiler is disabled.
• The userChrome.css and userContent.css files are ignored.
• The default toolbar layout is used.
• Hardware acceleration is disabled.

Safe Mode has no effect on the following:

• The status of plugins is not affected.
• Custom preferences are not affected.

So, it is unlikely to be plugins as they were still running in Safe Mode.

If you have nothing in the 'Extensions' section: Do you have anything in the Dictionaries section?

Test: Restart normally, then in Tools > add-ons Select the 'Dictionaries' icon and disable all dictionaries. then test the Write button to see if window is opening ok.

I have no extensions at all. No dictionaries.

I am using the default theme.

I am using the default tool bars.

I can only open/write a new message when program is in safe mode.

Please follow these steps and see if they fix the problem:

1. Close Thunderbird if it is currently running.
2. Navigate to your Thunderbird profile as described in this article: Finding your profile.
3. Select the file named userChrome.css, and delete it (or move it to another folder temporarily). This will reset Thunderbird's interface to the default settings.
4. Run Thunderbird and hopefully the problem will be fixed.

re : file named userChrome.css, and delete it (or move it to another folder temporarily). This will reset Thunderbird's interface to the default settings.

The file userchrome.css will only exist if you have created it. If you have never created a chrome folder nor a userChrome.css or userContent.css files which would be located in the chrome folder in your profile folder name, then this does not apply.

What operating system are you using?

I suggest you try disabling the hardware acceleration.

In Thunderbird. If Windows OS:- 'Tools' > 'Options' > 'Advanced' > 'General' tab

If MAC Thunderbird > Preferences > > 'Advanced' > 'General' tab

click on 'Config Editor' button. it will tell you to be careful :) In top search type: gfx look for this line: gfx.direct2d.disabled; Value = false Double click on that line to toggle the 'false' to a 'true'

In top search type : layers look for this line : layers.acceleration.disabled; Value = false Double click on that line to toggle the 'false' to a 'true'

If you are using Linux or MAC OS X: try setting layers.prefer-opengl = true instead, to see if you can use OpenGL for the hardware acceleration instead.

Close the window - top right X click on OK

Close and restart Thunderbird. Test the Write window.