diff --git a/src/Preferences/HandleExtensions.gd b/src/Preferences/HandleExtensions.gd
index 0de438893..211a3e3a9 100644
--- a/src/Preferences/HandleExtensions.gd
+++ b/src/Preferences/HandleExtensions.gd
@@ -80,10 +80,10 @@ func _ready() -> void:
 		_add_extension(file_name)
 
 
+## This is an empty function at the moment, but internal extensions here should be added here
+## For example:
+## [code]read_extension("ExtensionName", true)[/code]
 func _add_internal_extensions() -> void:
-	## at the moment this is an empty function but you should add all internal extensions here
-	# for example:
-	#read_extension("ExtensionName", true)
 	pass
 
 
@@ -180,7 +180,7 @@ func _add_extension(file_name: String) -> void:
 	read_extension(file_name)
 
 
-func read_extension(extension_file_or_folder_name: StringName, internal := false):
+func read_extension(extension_file_or_folder_name: StringName, internal := false) -> void:
 	var file_name_no_ext := extension_file_or_folder_name.get_basename()
 	var extension_path := "res://src/Extensions/%s/" % file_name_no_ext
 	var extension_config_file_path := extension_path.path_join("extension.json")
diff --git a/src/UI/Buttons/PatternsPopup.gd b/src/UI/Buttons/PatternsPopup.gd
index 51f59612d..d2dffbeff 100644
--- a/src/UI/Buttons/PatternsPopup.gd
+++ b/src/UI/Buttons/PatternsPopup.gd
@@ -1,7 +1,7 @@
 class_name Patterns
 extends PopupPanel
 
-signal pattern_selected(pattern)
+signal pattern_selected(pattern: Pattern)
 
 var default_pattern: Pattern = null
 
@@ -31,10 +31,10 @@ func create_button(image: Image) -> Node:
 
 
 func add(image: Image, hint := "") -> void:
-	var button = create_button(image)
+	var button := create_button(image)
 	button.pattern.image = image
 	button.tooltip_text = hint
-	var container = get_node("ScrollContainer/PatternContainer")
+	var container := get_node("ScrollContainer/PatternContainer")
 	container.add_child(button)
 	button.pattern.index = button.get_index()
 
@@ -44,7 +44,7 @@ func add(image: Image, hint := "") -> void:
 
 func get_pattern(index: int) -> Pattern:
 	var container = Global.patterns_popup.get_node("ScrollContainer/PatternContainer")
-	var pattern = default_pattern
+	var pattern := default_pattern
 	if index < container.get_child_count():
 		pattern = container.get_child(index).pattern
 	return pattern
diff --git a/src/UI/Canvas/MouseGuide.gd b/src/UI/Canvas/MouseGuide.gd
index 6019659b0..7209f0819 100644
--- a/src/UI/Canvas/MouseGuide.gd
+++ b/src/UI/Canvas/MouseGuide.gd
@@ -19,7 +19,7 @@ func _ready() -> void:
 	draw_guide_line()
 
 
-func draw_guide_line():
+func draw_guide_line() -> void:
 	if type == Types.HORIZONTAL:
 		points[0] = Vector2(-19999, 0)
 		points[1] = Vector2(19999, 0)
diff --git a/src/UI/Canvas/ReferenceImages.gd b/src/UI/Canvas/ReferenceImages.gd
index ae1a77fc5..be96a5aa2 100644
--- a/src/UI/Canvas/ReferenceImages.gd
+++ b/src/UI/Canvas/ReferenceImages.gd
@@ -229,7 +229,7 @@ func get_transformed_rect_polygon(rect: Rect2, t: Transform2D) -> PackedVector2A
 	return final
 
 
-func populate_reference_menu(items: Array[ReferenceImage], default := false):
+func populate_reference_menu(items: Array[ReferenceImage], default := false) -> void:
 	reference_menu.clear()
 	# Default / Reset
 	if default:
@@ -320,7 +320,7 @@ func _draw() -> void:
 	# If we are dragging show where the Reference was coming from
 	if dragging:
 		var i: ReferenceImage = Global.current_project.get_current_reference_image()
-		var prev_transform = Transform2D(og_rotation, og_scale, 0.0, og_pos)
+		var prev_transform := Transform2D(og_rotation, og_scale, 0.0, og_pos)
 		var prev_poly := get_transformed_rect_polygon(i.get_rect(), prev_transform)
 		prev_poly.append(prev_poly[0])
 		draw_polyline(prev_poly, Color(1, 0.29, 0.29), line_width)
diff --git a/src/UI/Canvas/Selection.gd b/src/UI/Canvas/Selection.gd
index ce030a65c..0b8bd2682 100644
--- a/src/UI/Canvas/Selection.gd
+++ b/src/UI/Canvas/Selection.gd
@@ -807,7 +807,7 @@ func delete(selected_cels := true) -> void:
 
 ## Makes a project brush out of the current selection's content.
 func new_brush() -> void:
-	var brush = get_enclosed_image()
+	var brush := get_enclosed_image()
 	if brush and !brush.is_invisible():
 		var brush_used: Image = brush.get_region(brush.get_used_rect())
 		Global.current_project.brushes.append(brush_used)
diff --git a/src/UI/ColorPickers/ColorPicker.gd b/src/UI/ColorPickers/ColorPicker.gd
index f89ebdda5..567f05d1e 100644
--- a/src/UI/ColorPickers/ColorPicker.gd
+++ b/src/UI/ColorPickers/ColorPicker.gd
@@ -121,11 +121,11 @@ func _average(color_1: Color, color_2: Color) -> void:
 	average_color.color = average
 
 
-func _on_CopyAverage_button_down():
+func _on_CopyAverage_button_down() -> void:
 	average_color.visible = false
 
 
-func _on_CopyAverage_button_up():
+func _on_CopyAverage_button_up() -> void:
 	average_color.visible = true
 
 
diff --git a/src/UI/Dialogs/TileModeOffsetsDialog.gd b/src/UI/Dialogs/TileModeOffsetsDialog.gd
index 2d79a4f77..e3e264571 100644
--- a/src/UI/Dialogs/TileModeOffsetsDialog.gd
+++ b/src/UI/Dialogs/TileModeOffsetsDialog.gd
@@ -45,7 +45,7 @@ func _on_TileModeOffsetsDialog_about_to_show() -> void:
 	update_preview()
 
 
-func _show_options():
+func _show_options() -> void:
 	x_basis_x_spinbox.visible = true
 	x_basis_y_spinbox.visible = true
 	y_basis_x_spinbox.visible = true
@@ -102,12 +102,12 @@ func _on_TileModeOffsetsDialog_visibility_changed() -> void:
 	Global.dialog_open(false)
 
 
-func _on_TileModeOffsetsDialog_size_changed():
+func _on_TileModeOffsetsDialog_size_changed() -> void:
 	if tile_mode:
 		update_preview()
 
 
-func _on_Reset_pressed():
+func _on_Reset_pressed() -> void:
 	tile_mode.tiles.x_basis = Vector2i(Global.current_project.size.x, 0)
 	tile_mode.tiles.y_basis = Vector2i(0, Global.current_project.size.y)
 	x_basis_x_spinbox.value = Global.current_project.size.x
@@ -117,7 +117,7 @@ func _on_Reset_pressed():
 	update_preview()
 
 
-func change_mask():
+func change_mask() -> void:
 	if Global.current_project.tiles.mode == Tiles.MODE.NONE:
 		return
 	var frame_idx := Global.current_project.current_frame
@@ -135,7 +135,7 @@ func change_mask():
 		load_mask(image)
 
 
-func load_mask(image: Image):
+func load_mask(image: Image) -> void:
 	Global.current_project.tiles.tile_mask = image
 	Global.current_project.tiles.has_mask = true
 
diff --git a/src/UI/PerspectiveEditor/LineButton.tscn b/src/UI/PerspectiveEditor/LineButton.tscn
index 929c98df4..a8c07df7e 100644
--- a/src/UI/PerspectiveEditor/LineButton.tscn
+++ b/src/UI/PerspectiveEditor/LineButton.tscn
@@ -1,49 +1,40 @@
-[gd_scene load_steps=3 format=2]
+[gd_scene load_steps=3 format=3 uid="uid://collailpx6ft5"]
 
-[ext_resource path="res://src/UI/Nodes/ValueSlider.tscn" type="PackedScene" id=1]
-[ext_resource path="res://src/UI/Nodes/CollapsibleContainer.gd" type="Script" id=3]
+[ext_resource type="PackedScene" uid="uid://yjhp0ssng2mp" path="res://src/UI/Nodes/ValueSlider.tscn" id="1"]
+[ext_resource type="Script" path="res://src/UI/Nodes/CollapsibleContainer.gd" id="3"]
 
 [node name="LineButton" type="VBoxContainer"]
 offset_right = 159.0
 offset_bottom = 20.0
-theme_type_variation = "CollapsibleContainer"
-script = ExtResource( 3 )
+theme_type_variation = &"CollapsibleContainer"
+script = ExtResource("3")
 
 [node name="HBoxContainer" type="HBoxContainer" parent="."]
 visible = false
-offset_top = 24.0
-offset_right = 159.0
-offset_bottom = 76.0
+layout_mode = 2
 
 [node name="Spacer" type="Control" parent="HBoxContainer"]
-offset_right = 20.0
-offset_bottom = 52.0
-custom_minimum_size = Vector2( 20, 0 )
+custom_minimum_size = Vector2(20, 0)
+layout_mode = 2
 
 [node name="VSeparator" type="VSeparator" parent="HBoxContainer"]
-offset_left = 24.0
-offset_right = 28.0
-offset_bottom = 52.0
+layout_mode = 2
 
 [node name="Properties" type="VBoxContainer" parent="HBoxContainer"]
-offset_left = 32.0
-offset_right = 83.0
-offset_bottom = 52.0
+layout_mode = 2
 size_flags_horizontal = 3
 
-[node name="AngleSlider" parent="HBoxContainer/Properties" instance=ExtResource( 1 )]
-offset_right = 51.0
+[node name="AngleSlider" parent="HBoxContainer/Properties" instance=ExtResource("1")]
+layout_mode = 2
 max_value = 359.999
 step = 0.001
 allow_greater = true
 prefix = "Angle:"
 suffix = "°"
 
-[node name="LengthSlider" parent="HBoxContainer/Properties" instance=ExtResource( 1 )]
+[node name="LengthSlider" parent="HBoxContainer/Properties" instance=ExtResource("1")]
 unique_name_in_owner = true
-offset_top = 28.0
-offset_right = 51.0
-offset_bottom = 52.0
+layout_mode = 2
 min_value = 1.0
 max_value = 19999.0
 value = 19999.0
@@ -52,12 +43,8 @@ prefix = "Length:"
 suffix = "px"
 
 [node name="Delete" type="Button" parent="HBoxContainer"]
-offset_left = 87.0
-offset_right = 151.0
-offset_bottom = 52.0
+layout_mode = 2
 text = "Remove"
 
 [node name="VSeparator2" type="VSeparator" parent="HBoxContainer"]
-offset_left = 155.0
-offset_right = 159.0
-offset_bottom = 52.0
+layout_mode = 2
diff --git a/src/UI/PerspectiveEditor/PerspectiveEditor.gd b/src/UI/PerspectiveEditor/PerspectiveEditor.gd
index ab9c6641c..f9ed1077d 100644
--- a/src/UI/PerspectiveEditor/PerspectiveEditor.gd
+++ b/src/UI/PerspectiveEditor/PerspectiveEditor.gd
@@ -55,7 +55,7 @@ func delete_point(idx: int) -> void:
 
 
 func do_delete_point(idx: int) -> void:
-	var point = vanishing_point_container.get_child(idx)
+	var point := vanishing_point_container.get_child(idx)
 	delete_pool.append(point.serialize())
 	point.queue_free()
 	point.update_data_to_project(true)
diff --git a/src/UI/PerspectiveEditor/PerspectiveLine.gd b/src/UI/PerspectiveEditor/PerspectiveLine.gd
index 6e3ff00dc..7e55c022e 100644
--- a/src/UI/PerspectiveEditor/PerspectiveLine.gd
+++ b/src/UI/PerspectiveEditor/PerspectiveLine.gd
@@ -7,10 +7,10 @@ const CIRCLE_RAD := 4
 var angle := 0
 var length := 19999
 
-var is_hidden = false
+var is_hidden := false
 var has_focus := false
 var track_mouse := false
-var change_length = false
+var change_length := false
 
 var line_button: Node
 var _vanishing_point: Node
@@ -20,14 +20,14 @@ func serialize() -> Dictionary:
 	return {"angle": angle, "length": length}
 
 
-func deserialize(data: Dictionary):
+func deserialize(data: Dictionary) -> void:
 	if data.has("angle"):
 		angle = data.angle
 	if data.has("length"):
 		length = data.length
 
 
-func initiate(data: Dictionary, vanishing_point: Node):
+func initiate(data: Dictionary, vanishing_point: Node) -> void:
 	_vanishing_point = vanishing_point
 	Global.canvas.add_child(self)
 	deserialize(data)
@@ -37,12 +37,12 @@ func initiate(data: Dictionary, vanishing_point: Node):
 	refresh()
 
 
-func refresh():
+func refresh() -> void:
 	default_color = _vanishing_point.color
 	draw_perspective_line()
 
 
-func draw_perspective_line():
+func draw_perspective_line() -> void:
 	var start := Vector2(_vanishing_point.pos_x.value, _vanishing_point.pos_y.value)
 	points[0] = start
 	if is_hidden:
@@ -53,7 +53,7 @@ func draw_perspective_line():
 		)
 
 
-func hide_perspective_line():
+func hide_perspective_line() -> void:
 	var start := Vector2(_vanishing_point.pos_x.value, _vanishing_point.pos_y.value)
 	points[1] = start
 	is_hidden = true
@@ -88,7 +88,7 @@ func _input(event: InputEvent) -> void:
 		queue_redraw()
 
 
-func try_rotate_scale():
+func try_rotate_scale() -> void:
 	var mouse_point := Global.canvas.current_pixel
 	var project_size := Global.current_project.size
 	var test_line := (points[1] - points[0]).rotated(deg_to_rad(90)).normalized()
diff --git a/src/UI/PerspectiveEditor/VanishingPoint.gd b/src/UI/PerspectiveEditor/VanishingPoint.gd
index 15b9ba51a..b828b7c1a 100644
--- a/src/UI/PerspectiveEditor/VanishingPoint.gd
+++ b/src/UI/PerspectiveEditor/VanishingPoint.gd
@@ -5,10 +5,10 @@ var perspective_lines := []
 var color := Color(randf(), randf(), randf(), 1)
 
 var tracker_line: PerspectiveLine
-@onready var color_picker_button = $"%ColorPickerButton"
+@onready var color_picker_button := $"%ColorPickerButton" as ColorPickerButton
 @onready var title := $"%PointCollapseContainer"
-@onready var pos_x := $"%X"
-@onready var pos_y := $"%Y"
+@onready var pos_y := $"%Y" as ValueSlider
+@onready var pos_x := $"%X" as ValueSlider
 @onready var line_buttons_container := $"%LinesContainer"
 @onready var boundary_l := $Content/BoundaryL
 @onready var boundary_r := $Content/BoundaryR
@@ -19,7 +19,7 @@ func serialize() -> Dictionary:
 	var lines_data := []
 	for line in perspective_lines:
 		lines_data.append(line.serialize())
-	var data = {
+	var data := {
 		"pos_x": pos_x.value,
 		"pos_y": pos_y.value,
 		"lines": lines_data,
@@ -28,7 +28,7 @@ func serialize() -> Dictionary:
 	return data
 
 
-func deserialize(start_data: Dictionary):
+func deserialize(start_data: Dictionary) -> void:
 	if start_data:  # Data is not {} means the project knows about this point
 		if start_data.has("pos_x") and start_data.has("pos_y"):
 			pos_x.value = start_data.pos_x
@@ -47,7 +47,7 @@ func deserialize(start_data: Dictionary):
 	update_boundary_color()
 
 
-func initiate(start_data: Dictionary = {}, idx = -1) -> void:
+func initiate(start_data := {}, idx := -1) -> void:
 	deserialize(start_data)
 	# Title of Vanishing point button
 	if idx != -1:  # If the initialization is part of a Redo
@@ -60,7 +60,7 @@ func initiate(start_data: Dictionary = {}, idx = -1) -> void:
 	pos_y.value_changed.connect(_on_pos_value_changed)
 
 
-func update_boundary_color():
+func update_boundary_color() -> void:
 	var luminance := (0.2126 * color.r) + (0.7152 * color.g) + (0.0722 * color.b)
 	color.a = 0.9 - luminance * 0.4  # Interpolates between 0.5 to 0.9
 	boundary_l.color = color
@@ -68,10 +68,10 @@ func update_boundary_color():
 	boundary_b.color = color
 
 
-func _input(_event: InputEvent):
-	var mouse_point = Global.canvas.current_pixel
-	var project_size = Global.current_project.size
-	var start = Vector2(pos_x.value, pos_y.value)
+func _input(_event: InputEvent) -> void:
+	var mouse_point := Global.canvas.current_pixel
+	var project_size := Global.current_project.size
+	var start := Vector2(pos_x.value, pos_y.value)
 	if (
 		Input.is_action_just_pressed("left_mouse")
 		and Global.can_draw
@@ -104,7 +104,7 @@ func _on_Delete_pressed() -> void:
 	Global.perspective_editor.delete_point(get_index())
 
 
-func _on_color_changed(_color: Color):
+func _on_color_changed(_color: Color) -> void:
 	update_boundary_color()
 	color = _color
 	refresh(-1)
@@ -116,32 +116,32 @@ func _on_pos_value_changed(_value: float) -> void:
 	update_data_to_project()
 
 
-func angle_changed(value: float, line_button):
+func angle_changed(value: float, line_button: Node) -> void:
 	# check if the properties are changing the line or is the line changing properties
-	var angle_slider = line_button.find_child("AngleSlider")
+	var angle_slider := line_button.find_child("AngleSlider")
 	if angle_slider.value != value:  # the line is changing the properties
 		angle_slider.value = value
 	else:
-		var line_index = line_button.get_index()
+		var line_index := line_button.get_index()
 		perspective_lines[line_index].angle = value
 		refresh(line_index)
 	update_data_to_project()
 
 
-func length_changed(value: float, line_button):
+func length_changed(value: float, line_button: Node) -> void:
 	# check if the properties are changing the line or is the line changing properties
-	var length_slider = line_button.find_child("LengthSlider")
+	var length_slider := line_button.find_child("LengthSlider")
 	if length_slider.value != value:  # the line is changing the properties
 		length_slider.value = value
 	else:
-		var line_index = line_button.get_index()
+		var line_index := line_button.get_index()
 		perspective_lines[line_index].length = value
 		refresh(line_index)
 	update_data_to_project()
 
 
-func _remove_line_pressed(line_button):
-	var index = line_button.get_index()
+func _remove_line_pressed(line_button: Node) -> void:
+	var index := line_button.get_index()
 	remove_line(index)
 	line_button.queue_free()
 	update_data_to_project()
@@ -159,7 +159,7 @@ func generate_line_data(initial_data: Dictionary = {}) -> Dictionary:
 	return line_data
 
 
-func add_line(loaded_line_data := {}, is_tracker := false):
+func add_line(loaded_line_data := {}, is_tracker := false) -> void:
 	var p_size := Global.current_project.size  # for use later in function
 
 	# Note: line_data will automatically get default values if loaded_line_data = {}
@@ -190,7 +190,7 @@ func add_line(loaded_line_data := {}, is_tracker := false):
 	else:  # Settings for Normal mode
 		var line_button := preload("res://src/UI/PerspectiveEditor/LineButton.tscn").instantiate()
 		line_buttons_container.add_child(line_button)
-		var index = line_button.get_parent().get_child_count() - 2
+		var index := line_button.get_parent().get_child_count() - 2
 		line_button.get_parent().move_child(line_button, index)
 
 		var line_name := str("Line", line_button.get_index() + 1, " (", absi(line_data.angle), "°)")
@@ -210,13 +210,13 @@ func add_line(loaded_line_data := {}, is_tracker := false):
 		perspective_lines.append(line)
 
 
-func remove_line(line_index):
+func remove_line(line_index: int) -> void:
 	var line_to_remove = perspective_lines[line_index]
 	perspective_lines.remove_at(line_index)
 	line_to_remove.queue_free()
 
 
-func update_data_to_project(removal := false):
+func update_data_to_project(removal := false) -> void:
 	var project := Global.current_project
 	var idx := get_index()
 	# If deletion is requested
@@ -233,7 +233,7 @@ func update_data_to_project(removal := false):
 	Global.current_project.has_changed = true
 
 
-func refresh(index: int):
+func refresh(index: int) -> void:
 	if index == -1:  # means all lines should be refreshed (including the tracker line)
 		refresh_tracker()
 		for i in perspective_lines.size():
@@ -242,15 +242,15 @@ func refresh(index: int):
 		refresh_line(index)
 
 
-func refresh_line(index: int):
-	var line_button = line_buttons_container.get_child(index)
+func refresh_line(index: int) -> void:
+	var line_button := line_buttons_container.get_child(index)
 	var line_data = perspective_lines[index].serialize()
 	var line_name := str("Line", line_button.get_index() + 1, " (", absi(line_data.angle), "°)")
 	line_button.text = line_name
 	perspective_lines[index].refresh()
 
 
-func refresh_tracker():
+func refresh_tracker() -> void:
 	tracker_line.refresh()
 
 
diff --git a/src/UI/ReferenceImages/ReferenceEdit.gd b/src/UI/ReferenceImages/ReferenceEdit.gd
index 1a4ddb30d..e52f684fe 100644
--- a/src/UI/ReferenceImages/ReferenceEdit.gd
+++ b/src/UI/ReferenceImages/ReferenceEdit.gd
@@ -14,7 +14,7 @@ func _ready() -> void:
 	references_container.reference_image_changed.connect(_on_reference_image_changed)
 
 
-func _update_properties():
+func _update_properties() -> void:
 	var ri: ReferenceImage = Global.current_project.get_current_reference_image()
 	if !ri:
 		return
@@ -121,7 +121,7 @@ func _on_Filter_toggled(pressed: bool) -> void:
 	ri.filter = pressed
 
 
-func _on_Reset_pressed():
+func _on_Reset_pressed() -> void:
 	var ri: ReferenceImage = Global.current_project.get_current_reference_image()
 	if !ri:
 		return
@@ -130,7 +130,7 @@ func _on_Reset_pressed():
 	references_container.commit_undo("Reset Reference Image Position", undo_data_tmp)
 
 
-func _on_Remove_pressed():
+func _on_Remove_pressed() -> void:
 	var ri: ReferenceImage = Global.current_project.get_current_reference_image()
 	if !ri:
 		return
@@ -146,7 +146,7 @@ func _on_Remove_pressed():
 			Global.dialog_open(true)
 
 
-func _on_X_value_changed(value: float):
+func _on_X_value_changed(value: float) -> void:
 	if _ignore_spinbox_changes:
 		return
 	var ri: ReferenceImage = Global.current_project.get_current_reference_image()
@@ -158,7 +158,7 @@ func _on_X_value_changed(value: float):
 	ri.position.x = value
 
 
-func _on_Y_value_changed(value: float):
+func _on_Y_value_changed(value: float) -> void:
 	if _ignore_spinbox_changes:
 		return
 	var ri: ReferenceImage = Global.current_project.get_current_reference_image()
@@ -170,7 +170,7 @@ func _on_Y_value_changed(value: float):
 	ri.position.y = value
 
 
-func _on_Scale_value_changed(value: float):
+func _on_Scale_value_changed(value: float) -> void:
 	if _ignore_spinbox_changes:
 		return
 	var ri: ReferenceImage = Global.current_project.get_current_reference_image()
@@ -183,7 +183,7 @@ func _on_Scale_value_changed(value: float):
 	ri.scale.y = value / 100
 
 
-func _on_Rotation_value_changed(value: float):
+func _on_Rotation_value_changed(value: float) -> void:
 	if _ignore_spinbox_changes:
 		return
 	var ri: ReferenceImage = Global.current_project.get_current_reference_image()
@@ -195,7 +195,7 @@ func _on_Rotation_value_changed(value: float):
 	ri.rotation_degrees = value
 
 
-func _on_Overlay_color_changed(color: Color):
+func _on_Overlay_color_changed(color: Color) -> void:
 	if _ignore_spinbox_changes:
 		return
 	var ri: ReferenceImage = Global.current_project.get_current_reference_image()
@@ -207,7 +207,7 @@ func _on_Overlay_color_changed(color: Color):
 	ri.overlay_color = Color(color, ri.overlay_color.a)
 
 
-func _on_Opacity_value_changed(value: float):
+func _on_Opacity_value_changed(value: float) -> void:
 	if _ignore_spinbox_changes:
 		return
 	var ri: ReferenceImage = Global.current_project.get_current_reference_image()
@@ -219,7 +219,7 @@ func _on_Opacity_value_changed(value: float):
 	ri.overlay_color.a = value / 100
 
 
-func _on_ColorClamping_value_changed(value: float):
+func _on_ColorClamping_value_changed(value: float) -> void:
 	if _ignore_spinbox_changes:
 		return
 	var ri: ReferenceImage = Global.current_project.get_current_reference_image()
diff --git a/src/UI/Timeline/AnimationTimeline.gd b/src/UI/Timeline/AnimationTimeline.gd
index 2198ee75b..8bb9e8272 100644
--- a/src/UI/Timeline/AnimationTimeline.gd
+++ b/src/UI/Timeline/AnimationTimeline.gd
@@ -156,7 +156,7 @@ func _on_LayerVBox_resized() -> void:
 	adjust_scroll_container()
 
 
-func adjust_scroll_container():
+func adjust_scroll_container() -> void:
 	tag_spacer.custom_minimum_size.x = (
 		frame_scroll_container.global_position.x - tag_scroll_container.global_position.x
 	)
@@ -386,7 +386,7 @@ func copy_frames(
 		)
 	project.undos += 1
 	project.undo_redo.create_action("Add Frame")
-	var last_focus_cels = []
+	var last_focus_cels := []
 	for f in indices:
 		var src_frame := project.frames[f]
 		var new_frame := Frame.new()
@@ -453,7 +453,7 @@ func copy_frames(
 	project.undo_redo.add_do_method(project.add_frames.bind(copied_frames, copied_indices))
 	project.undo_redo.add_undo_method(project.remove_frames.bind(copied_indices))
 	if select_all_cels:
-		var all_new_cels = []
+		var all_new_cels := []
 		# Select all the new frames so that it is easier to move/offset collectively if user wants
 		# To ease animation workflow, new current frame is the first copied frame instead of the last
 		var range_start := copied_indices[-1]
@@ -884,7 +884,7 @@ func change_layer_order(up: bool) -> void:
 	for l in from_indices:
 		from_parents.append(project.layers[l].parent)
 	var to_parents := from_parents.duplicate()
-	var to_index = layer.index - child_count  # the index where the LOWEST shifted layer should end up
+	var to_index := layer.index - child_count  # the index where the LOWEST shifted layer should end up
 
 	if up:
 		var above_layer := project.layers[project.current_layer + 1]
@@ -1091,10 +1091,10 @@ func project_changed() -> void:
 		if layer < vbox_child_count:
 			var cel_hbox: HBoxContainer = Global.cel_vbox.get_child(vbox_child_count - 1 - layer)
 			if frame < cel_hbox.get_child_count():
-				var cel_button = cel_hbox.get_child(frame)
+				var cel_button := cel_hbox.get_child(frame)
 				cel_button.button_pressed = true
 
-			var layer_button = Global.layer_vbox.get_child(vbox_child_count - 1 - layer)
+			var layer_button := Global.layer_vbox.get_child(vbox_child_count - 1 - layer)
 			layer_button.button_pressed = true
 
 
diff --git a/src/UI/Timeline/FrameProperties.gd b/src/UI/Timeline/FrameProperties.gd
index b28428bb3..f25cd6847 100644
--- a/src/UI/Timeline/FrameProperties.gd
+++ b/src/UI/Timeline/FrameProperties.gd
@@ -1,8 +1,8 @@
 extends ConfirmationDialog
 
 var frame_indices := []
-@onready var frame_num = $GridContainer/FrameNum
-@onready var frame_dur = $GridContainer/FrameTime
+@onready var frame_num := $GridContainer/FrameNum
+@onready var frame_dur := $GridContainer/FrameTime
 
 
 func _on_FrameProperties_about_to_show() -> void:
diff --git a/src/UI/Timeline/FrameScrollContainer.gd b/src/UI/Timeline/FrameScrollContainer.gd
index dc9835d83..23d0650a1 100644
--- a/src/UI/Timeline/FrameScrollContainer.gd
+++ b/src/UI/Timeline/FrameScrollContainer.gd
@@ -5,7 +5,7 @@ const PADDING := 1
 @export var h_scroll_bar: HScrollBar
 
 
-func _ready():
+func _ready() -> void:
 	sort_children.connect(_on_sort_children)
 	if is_instance_valid(h_scroll_bar):
 		h_scroll_bar.resized.connect(_update_scroll)
@@ -34,7 +34,7 @@ func _update_scroll() -> void:
 			get_child(0).position.x = -h_scroll_bar.value + PADDING
 
 
-func ensure_control_visible(control: Control):
+func ensure_control_visible(control: Control) -> void:
 	if not is_instance_valid(control):
 		return
 	# Based on Godot's implementation in ScrollContainer
diff --git a/src/UI/Timeline/FrameTagDialog.gd b/src/UI/Timeline/FrameTagDialog.gd
index 2b90e218b..19a969965 100644
--- a/src/UI/Timeline/FrameTagDialog.gd
+++ b/src/UI/Timeline/FrameTagDialog.gd
@@ -6,7 +6,7 @@ var delete_tag_button: Button
 
 @onready var main_vbox_cont: VBoxContainer = $VBoxContainer/ScrollContainer/VBoxTagContainer
 @onready var add_tag_button: Button = $VBoxContainer/ScrollContainer/VBoxTagContainer/AddTag
-@onready var options_dialog = $TagOptions
+@onready var options_dialog := $TagOptions
 
 
 func _ready() -> void:
@@ -79,8 +79,8 @@ func _on_AddTag_pressed() -> void:
 
 
 func _on_EditButton_pressed(_tag_id: int, edit_button: Button) -> void:
-	var x_pos = edit_button.global_position.x
-	var y_pos = edit_button.global_position.y + 2 * edit_button.size.y
+	var x_pos := edit_button.global_position.x
+	var y_pos := edit_button.global_position.y + 2 * edit_button.size.y
 	options_dialog.popup(Rect2i(position + Vector2i(x_pos, y_pos), options_dialog.size))
 	current_tag_id = _tag_id
 	var animation_tag: AnimationTag = Global.current_project.animation_tags[_tag_id]
diff --git a/src/UI/Timeline/PasteTagPopup.gd b/src/UI/Timeline/PasteTagPopup.gd
index 278412900..e8d77039d 100644
--- a/src/UI/Timeline/PasteTagPopup.gd
+++ b/src/UI/Timeline/PasteTagPopup.gd
@@ -21,10 +21,10 @@ func _ready() -> void:
 func refresh_list() -> void:
 	animation_tags_list.clear()
 	for tag in from_project.animation_tags:
-		var img = Image.create(5, 5, true, Image.FORMAT_RGBA8)
+		var img := Image.create(5, 5, true, Image.FORMAT_RGBA8)
 		img.fill(tag.color)
-		var tex = ImageTexture.create_from_image(img)
-		var tag_title = tag.name
+		var tex := ImageTexture.create_from_image(img)
+		var tag_title := tag.name
 		if tag_title == "":
 			tag_title = "(Untitled)"
 		animation_tags_list.add_item(tag_title, tex)
@@ -60,7 +60,7 @@ func _on_FromProject_changed(id: int) -> void:
 
 func _on_TagList_id_pressed(id: int) -> void:
 	var tag: AnimationTag = from_project.animation_tags[id]
-	var frames = []
+	var frames := []
 	for i in range(tag.from - 1, tag.to):
 		frames.append(i)
 	if create_new_tags:
@@ -71,7 +71,7 @@ func _on_TagList_id_pressed(id: int) -> void:
 
 
 ## Gets frame indices of [member from_project] and dumps it in the current project.
-func add_animation(indices: Array, destination: int, from_tag: AnimationTag = null):
+func add_animation(indices: Array, destination: int, from_tag: AnimationTag = null) -> void:
 	var project: Project = Global.current_project
 	if from_project == project:  ## If we are copying tags within project
 		Global.animation_timeline.copy_frames(indices, destination, true, from_tag)
@@ -212,7 +212,7 @@ func add_animation(indices: Array, destination: int, from_tag: AnimationTag = nu
 	project.undo_redo.add_do_property(Global.current_project, "selected_cels", [])
 	project.undo_redo.add_undo_property(Global.current_project, "selected_cels", [])
 
-	var all_new_cels = []
+	var all_new_cels := []
 	# Select all the new frames so that it is easier to move/offset collectively if user wants
 	# To ease animation workflow, new current frame is the first copied frame instead of the last
 	var range_start: int = copied_indices[-1]
diff --git a/src/UI/TopMenuContainer/TopMenuContainer.gd b/src/UI/TopMenuContainer/TopMenuContainer.gd
index 66665175d..7297b4da0 100644
--- a/src/UI/TopMenuContainer/TopMenuContainer.gd
+++ b/src/UI/TopMenuContainer/TopMenuContainer.gd
@@ -485,8 +485,7 @@ func _on_open_last_project_file_menu_option_pressed() -> void:
 	if Global.config_cache.has_section_key("data", "last_project_path"):
 		Global.control.load_last_project()
 	else:
-		Global.error_dialog.set_text("You haven't saved or opened any project in Pixelorama yet!")
-		_popup_dialog(Global.error_dialog)
+		Global.popup_error("You haven't saved or opened any project in Pixelorama yet!")
 
 
 func _save_project_file() -> void: