[TYPO3-english] Extensions go blank in BE after upgrade

[yanagik317 at netscape.net]

Dear Typo3sters,

Following an upgrade to 4.4.12, I'm seeing some extensions (T3mootools, 
Powermail, etc) go blank in BE (Web -> Powermail).  I don't see PHP 
errors in logs.  Web pages that use them seem to be functional.  I'm 
not sure my upgrading mangled or it's no longer fully compatible.  At 
least with Powermail, its web page says it's tested through 4.2 but I 
don't see that it is or is not compatible with 4.4.x.  This may be a 
question to extension writers, but has anyone experienced something 
like this?

In general, my understanding of extensions is that you take them as-is 
and if it works it works and if it doesn't it doesn't, and if it 
doesn't work with the version of Typo3 you want to upgrade to, stop 
using it.  Am I more or less correct?

Thank you,

--Koji