Index: users.php
===================================================================
--- users.php	(revision 2981)
+++ users.php	(working copy)
@@ -20,13 +20,20 @@
 		die(__('You can’t edit users.'));
 
 	$userids = $_POST['users'];
+	$update = 'promote';
 	foreach($userids as $id) {
+		// The new role of the current user must also have edit_users caps
+		if($id == $current_user->id && !$wp_roles->role_objects[$_POST['new_role']]->has_cap('edit_users')) {
+			$update = 'err_admin_role';
+			continue;
+		}
+
 		$user = new WP_User($id);
 		$user->set_role($_POST['new_role']);
 	}
-		
-	header('Location: users.php?update=promote');
 
+	header('Location: users.php?update=' . $update);
+
 break;
 
 case 'dodelete':
@@ -42,7 +49,12 @@
 
 	$userids = $_POST['users'];
 	
+	$update = 'del';
 	foreach($userids as $id) {
+		if($id == $current_user->id) {
+			$update = 'err_admin_del';
+			continue;
+		}
 		switch($_POST['delete_option']) {
 		case 'delete':
 			wp_delete_user($id);
@@ -53,7 +65,7 @@
 		}
 	}
 
-	header('Location: users.php?update=del');
+	header('Location: users.php?update=' . $update);
 
 break;
 
@@ -78,21 +90,28 @@
 	<p><?php _e('You have specified these users for deletion:'); ?></p>
 	<ul>
 	<?php
+	$go_delete = false;
 	foreach($userids as $id) {
 		$user = new WP_User($id);
-		echo "<li><input type=\"hidden\" name=\"users[]\" value=\"{$id}\" />";
-		echo "{$id}: {$user->data->user_login}</li>\n";
+		if($id == $current_user->id) {
+			echo "<li>" . sprintf('ID #%1s: %2s <strong>The current user will not be deleted.</strong>', $id, $user->data->user_login) . "</li>\n";
+		}
+		else {
+			echo "<li><input type=\"hidden\" name=\"users[]\" value=\"{$id}\" />" . sprintf('ID #%1s: %2s', $id, $user->data->user_login) . "</li>\n";
+			$go_delete = true;
+		}
 	}
 	$all_logins = $wpdb->get_results("SELECT ID, user_login FROM $wpdb->users ORDER BY user_login");
 	$user_dropdown = '<select name="reassign_user">';
 	foreach($all_logins as $login) {
-		if(!in_array($login->ID, $userids)) {
+		if($login->ID == $current_user->id || !in_array($login->ID, $userids)) {
 			$user_dropdown .= "<option value=\"{$login->ID}\">{$login->user_login}</option>";
 		}
 	}
 	$user_dropdown .= '</select>';
 	?>
 	</ul>
+	<?php if($go_delete) : ?>
 	<p><?php _e('What should be done with posts and links owned by this user?'); ?></p>
 	<ul style="list-style:none;">
 		<li><label><input type="radio" id="delete_option0" name="delete_option" value="delete" checked="checked" />
@@ -102,6 +121,9 @@
 	</ul>
 	<input type="hidden" name="action" value="dodelete" />
 	<p class="submit"><input type="submit" name="submit" value="<?php _e('Confirm Deletion'); ?>" /></p>
+	<?php else : ?>
+	<p><?php _e('There are no valid users selected for deletion.'); ?></p>
+	<?php endif; ?>
 </div>
 </form>
 <?php
@@ -151,6 +173,18 @@
 			<div id="message" class="updated fade"><p><?php _e('Changed roles.'); ?></p></div>
 		<?php
 			break;
+		case 'err_admin_role':
+		?>
+			<div id="message" class="error"><p><?php _e('The current user\'s role must have user editing capabilities.'); ?></p></div>
+			<div id="message" class="updated fade"><p><?php _e('Other user roles have been changed.'); ?></p></div>
+		<?php
+			break;
+		case 'err_admin_del':
+		?>
+			<div id="message" class="error"><p><?php _e('You can\'t delete the current user.'); ?></p></div>
+			<div id="message" class="updated fade"><p><?php _e('Other users have been deleted.'); ?></p></div>
+		<?php
+			break;
 		}
 	endif; 
 	if ( isset($errors) ) : ?>