By blackwave

public OnPlayerCommandText(playerid,cmdtext[])
{
   if(strcmp("/text",cmdtext,true,10) == 0)
   {
        ShowPlayerDialog(playerid, 0, DIALOG_STYLE_INPUT, "Test", "Test", "do", "cancel");
        return 1;
   }
   return 0;
}

public OnDialogResponse(playerid, dialogid, response, listitem, inputtext[])
{
   if(dialogid == 0 && response)
   {
        new string[128];
        format(string,sizeof(string),"You typed: %s",inputtext);
        SendClientMessage(playerid, 0xFF48FFFF, string);
        return 1;
   }
   return 0;
}