Thank you for your help: but my problem was rather to restore the Control Panel/Windows Update window to its default position, at the centre of the screen (something you cannot do manually in an exact way)...
Anyway, after some experiments, I found that deleting these two Registry keys in Regedit (BTW, always back up the Registry, before editing it!) and rebooting restored the Control Panel/Windows Update window to its default position (centered, as it was before the VMware Tools installer "moved" it to the top left of the screen):
HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\BagMRU
HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\Bags
(The two keys in question will be automatically recreated, with default values.)
... So, problem solved!