diff --git a/AboutWindow.gd b/AboutWindow.gd
index ee2ad4f..67ffef3 100644
--- a/AboutWindow.gd
+++ b/AboutWindow.gd
@@ -1,3 +1,4 @@
+class_name AboutPopup
 extends PopupWindow
 
 @onready
diff --git a/MainWindow.gd b/MainWindow.gd
index b9ed7b7..db7f65a 100644
--- a/MainWindow.gd
+++ b/MainWindow.gd
@@ -1,3 +1,4 @@
+class_name MainWindow
 extends Control
 ## The main window: the top bar, the popups opened from it and the quiz below it.
 ##
@@ -11,22 +12,22 @@ var top_bar: TopBar = $TopBar
 var quiz: Quiz = $Quiz
 
 @onready
-var search_view: Control = $Search
+var search_view: SearchPopup = $Search
 
 @onready
-var sync_window: Control = %SyncWindow
+var sync_window: SyncPopup = %SyncWindow
 
 @onready
-var shortcuts_window: Control = %ShortcutsWindow
+var shortcuts_window: ShortcutsPopup = %ShortcutsWindow
 
 @onready
-var qr_window: Control = %QRWindow
+var qr_window: QRPopup = %QRWindow
 
 @onready
-var about_window: Control = %AboutWindow
+var about_window: AboutPopup = %AboutWindow
 
 @onready
-var log_window: Control = %Log
+var log_window: LogPopup = %Log
 
 @onready
 var statistic_popup: PopupPanel = $StatisticsPopupPanel
diff --git a/MusicListScrollContainer.gd b/MusicListScrollContainer.gd
index 0d63ea0..4523b0b 100644
--- a/MusicListScrollContainer.gd
+++ b/MusicListScrollContainer.gd
@@ -1,3 +1,4 @@
+class_name ScrollToEndContainer
 extends ScrollContainer
 
 var max_value = 0;
diff --git a/MusicPlayer.gd b/MusicPlayer.gd
index 29cd549..6ce9409 100644
--- a/MusicPlayer.gd
+++ b/MusicPlayer.gd
@@ -25,7 +25,7 @@ var sound_effect_player: AudioStreamPlayer = $AudioSoundEffectPlayer
 var progress_slider: HSlider = $PlayerBar/MusicPlayerContainer/MusicPlayerSlider
 
 @onready
-var volume_slider: HSlider = $PlayerBar/MusicPlayerContainer/VolumeSlider
+var volume_slider: VolumeSlider = $PlayerBar/MusicPlayerContainer/VolumeSlider
 
 @onready
 var music_time_label: Label = $PlayerBar/MusicPlayerContainer/MusicTimeLabel
diff --git a/PlayerNameField.gd b/PlayerNameField.gd
index 2d06140..206938a 100644
--- a/PlayerNameField.gd
+++ b/PlayerNameField.gd
@@ -1,3 +1,4 @@
+class_name PlayerNameField
 extends TextEdit
 
 signal enter_key_pressed
diff --git a/QRWindow.gd b/QRWindow.gd
index 336b1e8..b24b3e3 100644
--- a/QRWindow.gd
+++ b/QRWindow.gd
@@ -1,3 +1,4 @@
+class_name QRPopup
 extends PopupWindow
 
 @onready
diff --git a/SearchWindow.gd b/SearchWindow.gd
index f56fc72..64760a0 100644
--- a/SearchWindow.gd
+++ b/SearchWindow.gd
@@ -1,3 +1,4 @@
+class_name SearchPopup
 extends PopupWindow
 
 @onready
diff --git a/SettingsWindow.gd b/SettingsWindow.gd
index e9f927b..0836637 100644
--- a/SettingsWindow.gd
+++ b/SettingsWindow.gd
@@ -1,3 +1,4 @@
+class_name SettingsPopup
 extends PopupWindow
 
 @onready
diff --git a/log.gd b/log.gd
index 6ec7c59..d025b4f 100644
--- a/log.gd
+++ b/log.gd
@@ -1,3 +1,4 @@
+class_name LogPopup
 extends PopupWindow
 
 @onready
diff --git a/new_character_select.gd b/new_character_select.gd
index 42bebbf..8cf03b5 100644
--- a/new_character_select.gd
+++ b/new_character_select.gd
@@ -1,3 +1,4 @@
+class_name CharacterSelectPopup
 extends PopupWindow
 
 @onready
diff --git a/quiz.gd b/quiz.gd
index e12f0aa..f504c9b 100644
--- a/quiz.gd
+++ b/quiz.gd
@@ -33,10 +33,10 @@ var players_panel: PlayersPanel = $PlayersPanel
 var toolbar: QuizToolbar = $QuizToolbar
 
 @onready
-var settings_window: Control = $SettingsWindow
+var settings_window: SettingsPopup = $SettingsWindow
 
 @onready
-var winner_window: Control = %WinnerWindow
+var winner_window: WinnerPopup = %WinnerWindow
 
 @onready
 var song_controls: SongControls = $SongControls
@@ -48,7 +48,7 @@ var song_loader: SongLoader = $SongLoader
 var music_list_panel: MusicListPanel = $MusicListPanel
 
 @onready
-var new_character_select: Control = %NewCharacterSelect
+var new_character_select: CharacterSelectPopup = %NewCharacterSelect
 
 @onready
 var music_player_container: MusicPlayer = $MusicPlayer
diff --git a/shortcuts_window.gd b/shortcuts_window.gd
index 82e3c1c..9cd5064 100644
--- a/shortcuts_window.gd
+++ b/shortcuts_window.gd
@@ -1,3 +1,4 @@
+class_name ShortcutsPopup
 extends PopupWindow
 
 @onready
diff --git a/sync_window.gd b/sync_window.gd
index 652890a..021d7ce 100644
--- a/sync_window.gd
+++ b/sync_window.gd
@@ -1,3 +1,4 @@
+class_name SyncPopup
 extends PopupWindow
 
 @onready
diff --git a/volume_slider.gd b/volume_slider.gd
index 3e8751e..ffa168d 100644
--- a/volume_slider.gd
+++ b/volume_slider.gd
@@ -1,3 +1,4 @@
+class_name VolumeSlider
 extends HSlider
 
 @export
diff --git a/winner_window.gd b/winner_window.gd
index 1b4807e..94365b1 100644
--- a/winner_window.gd
+++ b/winner_window.gd
@@ -1,3 +1,4 @@
+class_name WinnerPopup
 extends PopupWindow
 
 @onready