Desktop icons are defined in the *.desktop files found in ~/Desktop . Some file manager want to be clever and smart and do not show the filenames but interpret their contents found inside those *.desktop text files a link to an icon and a name to be shown.

The easiest way to get such files is going to the menu and right click the mouse and select put to desktop. However going to /usr/share/applications and see what desktop files are already available and then just copy them to ~/Desktop. The *.desktop files is an other option. Since the *.desktop files are text files they can be edited using a text editor

There are also tools to create *.desktop files.

Path to the executable, Name on the desktop and finally an icon has to be placed. Icons for that can be found under /usr/share/icons or /usr/share/pixmaps for those directories no path and file extension must be added. For Icons in other directories the path must be present.

gtk-update-icon-cache /usr/share/icons/hicolor will show updates

Finally right click on the mouse lets to move menu icons to the desktop.

If a executable is not found add the path and use " characters

Exec="/opt/serna-free-4.4/bin/serna.sh"

The menu is made from *.desktop files in ~/.local/share/applications for user menus and /usr/share/applications for global menus. The parameter

Categories=Game

inside those files defines the category where they pop up. There is the java application lxmed that is a gui for this.

To have the terminal running:

Terminal=true

Inside the directory /usr/share/applications also a file mimeinfo.cache can be found. Having a file of a mime type, then the desktop file handling this type of data can be found. This cache file is created from the *.desktop files using their mime type declaration:

MimeType=video/dv;video/mpeg;video/x-mpeg;

File managers as pcmanfm make use of desktop files in /usr/share/applications that, when clicking on a file the mime type is defined (looking at the file extension) and via mimeinfo.cache the *.desktop file is found and therefore started including passing the name of the file being clicked.

In pcmanfm go to Edit/Preferences/General, Check box for "Don't ask options on launch executable file" to not have questions popping up

Desktop files can also be started automatically when they are put in /etc/xdg/autostart

Inside the *.desktop files there is the command including an variable as %f that represents a single file name.

xdg-open <filename> opens a file with the default application

xdg-settings get default-web-browser returns the desktop file of the default browser

gtk-launch <name of desktop file without .desktop> start such files