Ik denk dat ik het nu snap en heb dat in Ubuntu alsvolgt opgelost.
Show desktop button
1. Open terminal (Ctrl+Alt+T) and install xdotool :
sudo apt-get install xdotool
2. Then create the show desktop shortcut icon and edit it via command:
gedit ~/.local/share/applications/show-desktop.desktop
When the file opens, paste following lines and save it
[Desktop Entry]
Type=Application
Name=Show Desktop
Icon=desktop
Exec=xdotool key --clearmodifiers Super+d
3. Finally search for ‘show desktop’ in application menu, then right lick and select ‘add to
favorites’