UI Containers Container auto-layout, size flags, anchors, and split ratios define responsive UI systems. Available Scripts responsive_layout_builder.gd Expert container builder with breakpoint-based responsive layouts. responsive_grid.gd Auto-adjusting GridContainer that changes column count based on available width. Essential for responsive inventory screens and resizing windows. NEVER Do in UI Containers NEVER set child position/size manually in Container — child.position = Vector2(10, 10) inside HBoxContainer? Container overrides it on layout. Use custom_minimum_size OR margins instead. NEVER forget size_flags for expansion — Child in VBoxContainer doesn't expand? Default is SHRINK. Set size_flags_vertical = SIZE_EXPAND_FILL for fill behavior. NEVER use GridContainer without columns — GridContainer with default columns = 1 ? Vertical list, wrong layout. ALWAYS set columns property to grid width. NEVER nest too many containers — 10 levels of HBox in VBox in HBox? Re-layout overhead + hard to debug. Flatten OR use Control with custom layout. NEVER skip separation override — Default 4px separation? Cramped UI. Override with add_theme_constant_override("separation", value) for breathing room. NEVER use ScrollContainer without minimum size — ScrollContainer with no custom_minimum_size ? Expands infinitely, no scrolling. Set minimum OR use anchors.

VBoxContainer example

Automatically stacks children vertically

Children:

Button ("Play")

Button ("Settings")

Button ("Quit")

Set separation between items

$VBoxContainer . add_theme_constant_override ( "separation" , 10 ) Responsive Layout

Use anchors and size flags

func _ready ( ) -> void :

Expand to fill parent

$MarginContainer . set_anchors_preset ( Control . PRESET_FULL_RECT )

Add margins

$MarginContainer . add_theme_constant_override ( "margin_left" , 20 ) $MarginContainer . add_theme_constant_override ( "margin_right" , 20 ) SizeFlags

Control how children expand in containers

button . size_flags_horizontal = Control . SIZE_EXPAND_FILL button . size_flags_vertical = Control . SIZE_SHRINK_CENTER Reference Godot Docs: GUI Containers Related Master Skill: godot-master