Index: binaries/data/mods/public/gui/options/options.js
===================================================================
--- binaries/data/mods/public/gui/options/options.js    (revision 23405)
+++ binaries/data/mods/public/gui/options/options.js    (working copy)
@@ -140,7 +140,14 @@
        "initGUI": (option, control) => {
            control.list = option.list.map(e => e.label);
            control.list_data = option.list.map(e => e.value);
-       },
+           control.onHoverChange = () => {
+               let tooltip = option.tooltip;
+               let item = option.list[control.hovered];
+               if (item && item.tooltip)
+                   tooltip += "\n" + item.tooltip;
+               control.tooltip = tooltip;
+           };
+       }
    },
    "slider":
    {
Index: binaries/data/mods/public/gui/options/options.json
===================================================================
--- binaries/data/mods/public/gui/options/options.json  (revision 23405)
+++ binaries/data/mods/public/gui/options/options.json  (working copy)
@@ -63,9 +63,9 @@
                "tooltip": "Allow everybody or buddies only to join the game as observer after it started.",
                "config": "network.lateobservers",
                "list": [
-                   { "value": "everyone", "label": "Everyone" },
-                   { "value": "buddies", "label": "Buddies" },
-                   { "value": "disabled", "label": "Disabled" }
+                   { "value": "everyone", "label": "Everyone", "tooltip": "1" },
+                   { "value": "buddies", "label": "Buddies", "tooltip": "2"  },
+                   { "value": "disabled", "label": "Disabled", "tooltip": "3"  }
                ]
            },
            {