1. start a test mission
2. try with this code for example: pressing Space Key will show a text
```
disableSerialization;
waituntil {!isnull (finddisplay 46)};
_chat = (findDisplay 46) displayAddEventHandler ["KeyUp", {
params ["_display", "_key", "_shift", "_ctrl", "_alt"];
if (_key == 57) then {
systemChat "This DAddEventHandler should be removed/deleted after SP Mission Restart";
};
}];
```
3. restart game from menu and press Space key again