Reading `%clipboard%` not working with "text/plain" content

Reading the clipboard can fail when it was filled from a non-unicode html file. I assume that it only worked for me before because I stored my html files as unicode and thus calling %toClipboard()% created "text/unicode" data flavor.

Calling template:

%toclipboard("quickFilters")%
<div class="announcement">
<h2>Latest News</h2>
%file("../news-on-tb+addon.html")%   
</div>

included template news-on-tb+addon.html:

  <p>
    The Thunderbird Add-on <span class="productName">%clipboard%</span> 
    is now compatible with the latest version of Thunderbird (115.0).
  </p>
   ....

The string was copied to the clipboard by %toclipboard(..)% but couldn't be read by the included template file because of its format.

RealRaven2000 / SmartTemplates

Reading `%clipboard%` not working with "text/plain" content #264