Haven't found a way to workaround the problem. I tried turning off
various "Add-ons" to see if there was a bad interaction. No luck thus
far in pinning down the problem.
Found a workaround:
Symptom: TB 5.0 will not open a new window when doing very common
tasks such as replying to an email or creating a calendar event.
There is evidence that the new window should exist if you go to the
"Window" pull-down window. You can see that the window that was
supposed to be there even tho' in reality it is not.
Workaround:
In the "Help" pull-down menu, Select "Restart with Ad-ons Disabled".
You will then be promoted for other customizations such
as "Disable Add-ons". You only need t o check the box for "Restart TB
in Safe mode". Then TB works.
Symptom:
TB 5.0 refuses to open a new window for actions such as replying to an
email or opening an existing calendar event.
Problem:
TB new window manager gets confused about which virtual screen
the TB "Main and Newsgroups" window is currently located. When a
new pop-up window is required, the window is never rendered. However,
evidence of the invisible window(s) can be seen by going to the
"Window"
pull-down window. There, you will see all the windows that were
created
but never rendered.
Workaround:
Simply move the "Main and Newsgroups" window from its current virtual
window to another virtual screen. In my case, I used my mouse to drag
the window from my laptop screen over to my external monitor's screen.
Yeah, TB is useful once again.