Gum Forms Controls

Forms controls are interactive UI classes whose names mirror WPF (Button, CheckBox, TextBox, …), but they are laid out and rendered by Gum, not WPF. Reach for a Forms control for anything the player clicks, types in, or scrolls. For non-interactive HUD/decoration, use raw visuals instead (see below). Docs: https://docs.flatredball.com/gum/code/controls.

Common controls

Button, ToggleButton, RadioButton, CheckBox, Label, TextBox, PasswordBox, ComboBox, ListBox, Slider, ScrollBar, ScrollViewer, StackPanel, Panel, Menu, Window, Splitter.

Using a control in code

using Gum.Forms.Controls;

var button = new Button();
button.Text = "Play";
button.AddToRoot();               // adds it to the screen
button.Click += (_, _) => StartGame();

Text-bearing controls share this shape — new Label(), new TextBox(), etc. all expose .Text. Set position/size with Gum's unit system (see gum-layout), not WPF layout.

Composing controls (parenting in code)

AddToRoot() attaches a control to the screen. To nest one control inside another — buttons inside a panel, anything inside a container — call AddChild on the parent. There is no .Children.Add(...) on a Forms control.

var menu = new StackPanel();   // stacks its children; vertical by default
menu.Spacing = 8;              // gap between children (StackPanel.Spacing)
menu.AddToRoot();

var play = new Button { Text = "Play" };
var quit = new Button { Text = "Quit" };
menu.AddChild(play);           // parents the control under the panel
menu.AddChild(quit);

AddChild(child) sets the child's visual parent; the parent's layout then positions it — a StackPanel stacks them, and any container with ChildrenLayout set arranges them. RemoveChild undoes it. StackPanel defaults to Orientation.Vertical; set Orientation = Orientation.Horizontal for a row.

Forms vs raw visuals

Need	Use
Player interaction (click/type/scroll)	A Forms control
Static text	TextRuntime
Solid color block	ColoredRectangleRuntime
Image	SpriteRuntime
Scalable panel/border	NineSliceRuntime
Plain layout container	ContainerRuntime

Raw visuals: https://docs.flatredball.com/gum/code/standard-visuals.

Landmine: WPF conventions do not carry over

The names match WPF; the property model does not. On a Forms control:

• No Margin, Padding, or WPF-style HorizontalAlignment/VerticalAlignment. Position and size come from Gum units (X, XUnits, Width, WidthUnits, …).
• No Background, Foreground, or BorderBrush. Color and appearance come from states (below), not brush properties.
• No Visibility enum. Use the IsVisible bool.
• No WPF Auto sizing. A Button with Width = 128 is 128 px wide regardless of its text unless WidthUnits = RelativeToChildren. See gum-layout.

For a fuller WPF-to-Gum translation: https://docs.flatredball.com/gum/code/about/for-wpf-users.

The state / category system (how styling works)

Appearance is driven by named states grouped into a category on the control's visual, not by per-property setters. A Button's visual, for example, carries a category with Enabled, Highlighted, Pushed, Focused, and Disabled states; the control switches between them automatically as the player interacts. Each state sets a batch of variables (colors, sizes) at once.

To recognize this in code: applying a state name changes the look; the control does this for you on hover/press/focus. To customize appearance you edit the states (in the tool, or via the styling APIs) or swap in a different visual — you do not look for a Color property on the control. Don't panic when you see categories and states; they are Gum's equivalent of a style sheet. Styling guide: https://docs.flatredball.com/gum/code/styling.

Default visuals

A newly-constructed control (new Button()) gets a built-in default visual so it renders without any project. Replacing or restyling that visual is the styling story above. If a control looks unstyled or blank, its visual — not the control class — is what to inspect.