Fix some buttons not being affected by the custom icon color on startup

src/Autoload/Tools.gd

@@ -376,6 +376,7 @@ func add_tool_button(t: Tool, insert_pos := -1) -> void:
 	tool_button.get_node("BackgroundLeft").modulate = Global.left_tool_color
 	tool_button.get_node("BackgroundRight").modulate = Global.right_tool_color
 	tool_button.get_node("ToolIcon").texture = t.icon
+	tool_button.get_node("ToolIcon").modulate = Global.modulate_icon_color
 	tool_button.tooltip_text = t.generate_hint_tooltip()
 	t.button_node = tool_button
 	_tool_buttons.add_child(tool_button)

src/Preferences/RestoreDefaultButton.gd

@@ -10,6 +10,7 @@ var node: Node
 
 func _ready() -> void:
 	disabled = true
+	add_to_group(&"UIButtons")
 	modulate = Global.modulate_icon_color
 	texture_normal = preload("res://assets/graphics/misc/icon_reload.png")
 	texture_disabled = ImageTexture.new()

src/UI/Timeline/LayerButton.gd

@@ -42,7 +42,7 @@ func _ready() -> void:
 	custom_minimum_size.y = Global.animation_timeline.cel_size
 	label.text = layer.name
 	line_edit.text = layer.name
-	for child in get_children():
+	for child in $HBoxContainer.get_children():
 		if not child is Button:
 			continue
 		var texture := child.get_child(0)