I dont know whether this will work or not(I am not able to reproduce the
problem) but you may try
Select the vncviewer window press Shift Key (and keeping it pressed) select
any other window and release the shift key.
If this doesnt work try
Select any window (other than vncviewer) and press Shi
This sounds similar (but not quite the same) as a Windows issue I have
observed since at least Win95, maybe earlier. This affects all windows
applications.
The only fix I can usually apply is to press the offending stuck key, hoping
Windows will see the release event (careful because there are g