Here is a way to show and hide the desktop with a simple bin bash script and a .desktop file. First you need to get the program wmctrl because it will be the program handling the desktop effect ( minimize all & maximize all).
then after that installs run nano (or another editor) correctly and type the following script:
apt-get install wmctrl
Save the file to: Desktop.sh (or whatever) and then put the script in bin bash dir (for instance I'll put mine in the home dir for now). Then create a new .desktop file and type in the following:
if wmctrl -m | grep "mode: ON"; then
exec wmctrl -k off
exec wmctrl -k on
Comment=Show and Hide the Desktop
don't forget to include:
at the top of the .sh script!