diff --git a/gamemgr.php b/gamemgr.php
index 5a41b9b..e33ef15 100644
--- a/gamemgr.php
+++ b/gamemgr.php
@@ -90,7 +90,7 @@ function get_all_games()
 
 function patch_up_game_data(array &$game_data)
 {
-    $game_version = $game_data["version"] ?: 0;
+    $game_version = $game_data["version"] ?? 0;
     if ($game_version < 2) { // update to game version 2
         if (!key_exists("public_id", $game_data)) {
             $game_data["public"] = false;
diff --git a/globals.php b/globals.php
index 6981379..7ff05c3 100644
--- a/globals.php
+++ b/globals.php
@@ -15,6 +15,8 @@ const LOGIN_URL = "login.php";
 const MAIN_URL = "main.php";
 const SESSION_NAME = "spreadquiz_sid";
 
+const MISSING_IMAGE_PLACEHOLDER = "media/image-missing_120px.png";
+
 session_name(SESSION_NAME);
 
 // autoload session
diff --git a/groupmgr.php b/groupmgr.php
index bb467a6..b5ecee8 100644
--- a/groupmgr.php
+++ b/groupmgr.php
@@ -63,7 +63,7 @@ function change_group_user_assignments(string $groupid, $nickname_add, $nickname
     if (count($group_data) != 0) {
         // --------- UPDATE group assignments (DEV ONLY!)------
 
-        $group_data["editors"] = $group_data["editors"] ?: [];
+        $group_data["editors"] = $group_data["editors"] ?? [];
 
         // ---------
 
diff --git a/interface.php b/interface.php
index a7b69b6..ff9435e 100644
--- a/interface.php
+++ b/interface.php
@@ -22,7 +22,6 @@ require_once "testmgr.php";
 
 require_once "controller.php";
 
-const MISSING_IMAGE_PLACEHOLDER = "media/image-missing_120px.png";
 function patch_through_image(string $gameid, string $img_url)
 {
     $game_dir = get_game_dir_by_gameid($gameid);
@@ -105,14 +104,14 @@ switch ($action) {
         break;
     case "start_or_continue_test":
         {
-            $gameid = trim($_REQUEST["gameid"] ?: "");
+            $gameid = trim($_REQUEST["gameid"] ?? "");
             $testid = create_or_continue_test($gameid, $nickname);
             $result = $testid;
         }
         break;
     case "get_results_overview":
         {
-            $gameid = trim($_REQUEST["gameid"] ?: "");
+            $gameid = trim($_REQUEST["gameid"] ?? "");
             $concluded_tests = get_concluded_tests($gameid, $nickname);
             $overviews = [];
             foreach ($concluded_tests as $ct) {
@@ -130,50 +129,56 @@ switch ($action) {
 }
 
 // test-related queries
-$is_a_default_test_with_access = isset($_REQUEST["testid"]) && (($testid = trim($_REQUEST["testid"])) !== "") &&
-    ((count($test_data = get_test($testid))) > 0) && (($test_data["nickname"] === $nickname));
+const TEST_RELATED_ACTIONS = ["get_test", "save_answer", "submit_test"];
+if (in_array($action, TEST_RELATED_ACTIONS)) {
 
-$user_is_contributor_or_quizmaster = $is_quizmaster || is_user_contributor_to_game($test_data["gameid"], $nickname);
+    $testid = trim($_REQUEST["testid"] ?? "");
+    $test_data = ($testid !== "") ? get_test($testid) : [];
+    $is_a_default_test_with_access = ($testid !== "") && ((count($test_data)) > 0) && (($test_data["nickname"] === $nickname));
 
-if ($is_a_default_test_with_access || $user_is_contributor_or_quizmaster) {
+    $user_is_contributor_or_quizmaster = $is_quizmaster || is_user_contributor_to_game($test_data["gameid"], $nickname);
 
-    // update the test if timed
-    update_timed_tests([$test_data]);
+    if ($is_a_default_test_with_access || $user_is_contributor_or_quizmaster) {
 
-    switch ($action) {
-        case "get_test":
-            {
-                $test_data_with_current_time = $test_data;
-                $test_data_with_current_time["current_time"] = time();
-                $result = json_encode($test_data_with_current_time);
-            }
-            break;
-        case "save_answer":
-            {
-                $chidx = $_REQUEST["challenge_index"];
-                $answeridx = $_REQUEST["answer_index"];
-                save_answer($testid, $chidx, $answeridx);
-            }
-            break;
-        case "submit_test":
-            {
-                conclude_test($testid);
-            }
-            break;
-    }
-}
+        // update the test if timed
+        update_timed_tests([$test_data]);
 
-// $user_has_access_to_game = does_user_access_game($nickname, $gameid);
-
-// get_image needs special treatment
-if ($action === "get_image") {
-    if ($is_a_default_test_with_access || $user_is_contributor_or_quizmaster) { // default case
-        $img_url = trim($_REQUEST["img_url"] ?: "");
-        if ($img_url !== "") {
-            $gameid = $test_data["gameid"];
-            patch_through_image($gameid, $img_url);
+        switch ($action) {
+            case "get_test":
+                {
+                    $test_data_with_current_time = $test_data;
+                    $test_data_with_current_time["current_time"] = time();
+                    $result = json_encode($test_data_with_current_time);
+                }
+                break;
+            case "save_answer":
+                {
+                    $chidx = $_REQUEST["challenge_index"];
+                    $answeridx = $_REQUEST["answer_index"];
+                    save_answer($testid, $chidx, $answeridx);
+                }
+                break;
+            case "submit_test":
+                {
+                    conclude_test($testid);
+                }
+                break;
         }
     }
+
+    // $user_has_access_to_game = does_user_access_game($nickname, $gameid);
+
+    // get_image needs special treatment
+    if ($action === "get_image") {
+        if ($is_a_default_test_with_access || $user_is_contributor_or_quizmaster) { // default case
+            $img_url = trim($_REQUEST["img_url"] ?? "");
+            if ($img_url !== "") {
+                $gameid = $_REQUEST["gameid"];
+                patch_through_image($gameid, $img_url);
+            }
+        }
+    }
+
 }
 
 // creator or quizmaster actions
@@ -188,17 +193,17 @@ switch ($action) {
     case "update_game":
         {
             $update = $action === "update_game";
-            $data = json_decode($_REQUEST["data"], true) ?: [];
-            if (($data === []) || (trim($data["name"] ?: "") === "")) { // no further processing
+            $data = json_decode($_REQUEST["data"], true) ?? [];
+            if (($data === []) || (trim($data["name"] ?? "") === "")) { // no further processing
                 goto print_result; // ~exit...
             }
             $gameid = $data["_id"];
             $name = $data["name"];
             $description = $data["description"];
-            $contributors = explode_list($data["contributors"] ?: "");
-            $owner = $update ? trim($data["owner"] ?: $nickname) : $nickname;
-            $groups = explode_list($data["groups"] ?: "");
-            $properties = $data["properties"] ?: [];
+            $contributors = explode_list($data["contributors"] ?? "");
+            $owner = $update ? trim($data["owner"] ?? $nickname) : $nickname;
+            $groups = explode_list($data["groups"] ?? "");
+            $properties = $data["properties"] ?? [];
 
             $groupids = get_groupids_by_compounds($groups); // convert group compounds to _ids
 
@@ -277,7 +282,7 @@ switch ($action) {
                                 $zip->extractTo($game_dir . DIRECTORY_SEPARATOR);
 
                                 // search for the CSV table file
-                                $csv_files = glob($game_dir . DIRECTORY_SEPARATOR . "*.csv") ?: [];
+                                $csv_files = glob($game_dir . DIRECTORY_SEPARATOR . "*.csv") ?? [];
                                 if (count($csv_files)) {
                                     $challenge_import_status = import_challenges_from_csv($csv_files[0], $gameid);
                                 }
@@ -302,7 +307,7 @@ switch ($action) {
         break;
     case "get_challenges":
         {
-            $gameid = ($_REQUEST["gameid"] ?: "");
+            $gameid = ($_REQUEST["gameid"] ?? "");
             $game_data = get_game($gameid);
             if ((count($game_data) > 0) && ($is_quizmaster || (is_user_contributor_to_game($gameid, $requester_nickname)))) {
                 $result = file_get_contents(get_game_file_by_gameid($gameid));
@@ -311,7 +316,7 @@ switch ($action) {
         break;
     case "delete_games":
         {
-            $gameids = explode_list(trim($_REQUEST["ids"] ?: ""));
+            $gameids = explode_list(trim($_REQUEST["ids"] ?? ""));
             foreach ($gameids as $gameid) {
                 if (($gameid !== "") && (is_user_owner_of_the_game($gameid, $nickname))) { // only the owner may delete a game
                     delete_game($gameid);
@@ -321,7 +326,7 @@ switch ($action) {
         break;
     case "export_game_file_csv":
         {
-            $gameid = trim($_REQUEST["gameid"] ?: "");
+            $gameid = trim($_REQUEST["gameid"] ?? "");
             if (($gameid !== "") && is_user_contributor_to_game($gameid, $nickname)) {
                 $f = tmpfile();
                 header("Content-Type: text/csv");
@@ -334,9 +339,9 @@ switch ($action) {
         break;
     case "get_results_by_gameid":
         {
-            $gameid = trim($_REQUEST["gameid"] ?: "");
-            $filter = trim($_REQUEST["filter"] ?: "");
-            $ordering = trim($_REQUEST["orderby"] ?: "");
+            $gameid = trim($_REQUEST["gameid"] ?? "");
+            $filter = trim($_REQUEST["filter"] ?? "");
+            $ordering = trim($_REQUEST["orderby"] ?? "");
             if (($gameid !== "") && (is_user_contributor_to_game($gameid, $nickname) || $is_quizmaster)) {
                 $game_results = get_results_by_gameid($gameid, $filter, $ordering, true);
                 $result = json_encode($game_results);
@@ -345,20 +350,20 @@ switch ($action) {
         break;
     case "generate_detailed_stats":
         {
-            $testids = json_decode(trim($_REQUEST["testids"] ?: "[]"), true);
-            $gameid = trim($_REQUEST["gameid"] ?: "");
+            $testids = json_decode(trim($_REQUEST["testids"] ?? "[]"), true);
+            $gameid = trim($_REQUEST["gameid"] ?? "");
             $stats = generate_detailed_stats($gameid, $testids);
             $result = json_encode($stats);
         }
         break;
 
-    case "get_image":
-        {
-            $gameid = trim($_REQUEST["gameid"] ?: "");
-            $img_url = trim($_REQUEST["img_url"] ?: "");
-            patch_through_image($gameid, $img_url);
-        }
-        break;
+//    case "get_image":
+//        {
+//            $gameid = trim($_REQUEST["gameid"] ?? "");
+//            $img_url = trim($_REQUEST["img_url"] ?? "");
+//            patch_through_image($gameid, $img_url);
+//        }
+//        break;
 }
 
 // quizmaster actions
@@ -371,9 +376,9 @@ switch ($action) {
     case "update_group":
         {
             $update = $action === "update_group";
-            $groupname = trim($_REQUEST["groupname"] ?: "");
-            $description = trim($_REQUEST["description"] ?: "");
-            $editors = explode_list(trim($_REQUEST["editors"] ?: ""));
+            $groupname = trim($_REQUEST["groupname"] ?? "");
+            $description = trim($_REQUEST["description"] ?? "");
+            $editors = explode_list(trim($_REQUEST["editors"] ?? ""));
             $owner = (!$update) ? $user_data["nickname"] : trim($_REQUEST["owner"]);
             if ($owner === "") {
                 $owner = $user_data["nickname"];
@@ -404,7 +409,7 @@ switch ($action) {
         break;
     case "delete_groups":
         {
-            $groups = explode_list($_REQUEST["ids"] ?: "");
+            $groups = explode_list($_REQUEST["ids"] ?? "");
             foreach ($groups as $g) {
                 delete_group($g);
             }
@@ -415,7 +420,7 @@ switch ($action) {
         break;
     case "search_groups":
         {
-            $needle = $_REQUEST["needle"] ?: "";
+            $needle = $_REQUEST["needle"] ?? "";
             $result = json_encode(search_groups($needle));
         }
         break;
@@ -423,11 +428,11 @@ switch ($action) {
     case "update_user":
         {
             $update = $action === "update_user";
-            $target_nickname = trim($_REQUEST["nickname"] ?: "");
-            $password = trim($_REQUEST["password"] ?: "");
-            $groups = explode_list($_REQUEST["groups"] ?: "");
-            $realname = trim($_REQUEST["realname"] ?: "");
-            $privilege = trim($_REQUEST["privilege"] ?: PRIVILEGE_PLAYER);
+            $target_nickname = trim($_REQUEST["nickname"] ?? "");
+            $password = trim($_REQUEST["password"] ?? "");
+            $groups = explode_list($_REQUEST["groups"] ?? "");
+            $realname = trim($_REQUEST["realname"] ?? "");
+            $privilege = trim($_REQUEST["privilege"] ?? PRIVILEGE_PLAYER);
 
             $groupids = get_groupids_by_compounds($groups); // convert group compounds to _ids
 
@@ -469,7 +474,7 @@ switch ($action) {
         break;
     case "delete_users":
         {
-            $users = explode_list($_REQUEST["users"] ?: "");
+            $users = explode_list($_REQUEST["users"] ?? "");
             foreach ($users as $g) {
                 delete_user($g);
             }
diff --git a/js/common.js b/js/common.js
index cf616b9..4b2e6a3 100644
--- a/js/common.js
+++ b/js/common.js
@@ -1,7 +1,11 @@
-function unix_time_to_human_readable(tunix, date_delim = ". ") {
+function unix_time_to_human_readable(tunix) {
     const date = new Date(Number(tunix) * 1000);
-    return date.getFullYear() + date_delim + String(date.getMonth() + 1).padStart(2, "0") + date_delim + String(date.getDate()).padStart(2, "0") + ". "
-        + String(date.getHours()).padStart(2, "0") + ":" + String(date.getMinutes()).padStart(2, "0") + ":" + String(date.getSeconds()).padStart(2, "0");
+    return date.getFullYear() + "-" + String(date.getMonth() + 1).padStart(2, "0") + "-" + String(date.getDate()).padStart(2, "0") + " " +
+        String(date.getHours()).padStart(2, "0") + ":" + String(date.getMinutes()).padStart(2, "0") + ":" + String(date.getSeconds()).padStart(2, "0");
+}
+
+function human_readable_to_unix_time(hrtime) {
+    return (new Date(hrtime)).getTime() / 1000;
 }
 
 function seconds_to_time(s) {
diff --git a/js/result_analyzer.js b/js/result_analyzer.js
index 5044709..6160123 100644
--- a/js/result_analyzer.js
+++ b/js/result_analyzer.js
@@ -4,15 +4,46 @@ function create_cell(content = "") {
     return cell;
 }
 
+function autoconvert_datetime(str) {
+    // preprocess time fields in filter string
+    const dateTimeRE = /([0-9]{4}-[0-1][0-9]-[0-3][0-9] [0-2][0-9]:[0-5][0-9]:[0-5][0-9])/;
+    let filterParts = str.split(dateTimeRE);
+
+    // First, process full datetime entries
+    // datetime values will be at the odd indices
+    for (let i = 1; i < filterParts.length; i += 2) {
+        filterParts[i] = human_readable_to_unix_time(filterParts[i]);
+    }
+
+    // join the surrounding and converted parts
+    let filter = filterParts.join("");
+
+    // Now, process the only date parts
+    const dateRE = /([0-9]{4}-[0-1][0-9]-[0-3][0-9])/;
+    filterParts = filter.split(dateRE);
+
+    for (let i = 1; i < filterParts.length; i += 2) {
+        filterParts[i] = human_readable_to_unix_time(filterParts[i] + " 00:00:00");
+    }
+
+    filter = filterParts.join("");
+
+    return filter;
+}
+
 function fetch_results() {
 
     let filterF = document.getElementById("filter");
     let orderbyF = document.getElementById("orderby");
 
+    let filter = autoconvert_datetime(filterF.value.trim());
+
+    // ----------
+
     let req = {
         action: "get_results_by_gameid",
         gameid: GAMEID,
-        filter: filterF.value.trim(),
+        filter: filter.trim(),
         orderby: orderbyF.value.trim()
     };
 
diff --git a/result_analyzer.php b/result_analyzer.php
index bc7d779..44b62ae 100644
--- a/result_analyzer.php
+++ b/result_analyzer.php
@@ -36,6 +36,11 @@ if (!is_user_contributor_to_game($game_id, $user_data["nickname"]) && ($user_dat
     <script src="js/result_analyzer.js"></script>
     <link rel="stylesheet" href="style/spreadquiz.css">
     <link rel="stylesheet" href="style/quizmaster_area.css"/>
+    <style>
+        tbody#results_display > tr {
+            cursor: auto;
+        }
+    </style>
 </head>
 <body>
 
diff --git a/testground.php b/testground.php
index bc1f92e..ba052c3 100644
--- a/testground.php
+++ b/testground.php
@@ -8,9 +8,9 @@ if (!get_autologin_state() || !isset($_REQUEST["testid"])) {
     exit();
 }
 
-$testid = trim($_REQUEST["testid"] ?: "");
-$view_only = trim($_REQUEST["view_only"] ?: "false") === "true" ? true : false;
-$gameid = trim($_REQUEST["gameid"] ?: "");
+$testid = trim($_REQUEST["testid"] ?? "");
+$view_only = trim($_REQUEST["view_only"] ?? "false") === "true";
+$gameid = trim($_REQUEST["gameid"] ?? "");
 
 if ($testid === "") {
     exit();
diff --git a/testmgr.php b/testmgr.php
index 02b8ab7..133214e 100644
--- a/testmgr.php
+++ b/testmgr.php
@@ -187,8 +187,6 @@ function automatic_typecast(string $rval)
         } else { // is it a float?
             return (double)$rval;
         }
-    } elseif (str_starts_with($rval, 'T')) { // is it a date/time value?
-        return strtotime(substr($rval, 1)); // convert to UNIX timestamp
     } else { // it's a string
         return substr($rval, 1, strlen($rval) - 2); // strip leading and trailing quotes
     }