Go to Parallels Preferences (NOT the VM configuration), and choose Keyboard tab.
Choose the Windows Profile on the drilldown of profiles.
Make sure that the box beside "Parallels Desktop Shortcuts" is checked and double-click the last item, F6 - which is Show/Hide Application. Double-clicking opens an edit window. Change the F6 in the editable field to Cmd-H by clicking on the CMD icon and entering "h".
My "Virtual Machine Shortcuts" box is unchecked, but the "Enable Mac OS X Shortcuts" IS checked. Cmd-H works!
Last edited: Sep 15, 2011