Comment # 9 on bug 1178596 from Fabian Vogt

The issue initially reported here with "Unknown protocol 'mailto'" is actually
a different one than the one in the forum.

The one in the forum might be fixed by comment 5, but not the one here.

For the "Unknown protocol 'mailto'" case, please show the output of
"ktraderclient5 --mimetype x-scheme-handler/mailto". Does the first "exec" line
contain "%u"?