> For the complete documentation index, see [llms.txt](https://docs.flatredball.com/gum/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.flatredball.com/gum/code/controls/stackpanel.md).

# StackPanel

## Introduction

StackPanel is a container used to for controls which should stack vertically or horizontally, and which supports wrapping. StackPanels do not include any visual so they are always invisible.

## Backgrounds

StackPanels do not include any visuals, so they are always invisible on their own. To add a visible background behind a StackPanel, wrap it in a Panel with a ColoredRectangleRuntime. For details and a code example, see [Adding Backgrounds to Layout Containers](/gum/code/styling/code-only-styling/adding-and-removing-visual-children.md#adding-backgrounds-to-layout-containers).

## Code Example: Adding Buttons to a StackPanel

The following code shows how to add Button instances to a StackPanel. Notice that each button is automatically stacked vertically.

```csharp
// Initialize
var stackPanel = new StackPanel();
stackPanel.AddToRoot();
stackPanel.X = 50;
stackPanel.Y = 50;
stackPanel.Width = 200;

var random = new System.Random();
for (int i = 0; i < 10; i++)
{
    var button = new Button();
    stackPanel.AddChild(button);
    button.Text = "Button " + i;
    button.Height = 36;
    button.Click += (_, _) =>
        button.Text = DateTime.Now.ToString();
}
```

[Try on XnaFiddle.NET](https://xnafiddle.net/#snippet=H4sIAAAAAAAACm2PUUvDMBSF3wv9D5c-tXSEquiDs4JOUF9EtoIOCiOucb2svYH21qlj_90kdY6qeUnud07OSba-BxDct7ddHZwDN50aOYKEjLLCT2Vw8CYbaFku14-SVAUpkNrA7AeE0Tingy6uiiLTU635t_Bsrp4mQzb_hz1hwaXhx4kVcrL9jaRC1_vuj5ZVLaaOuZZX3UCIxIDGkozNdgFHdo_jKKdtTmCWzXnpmDV951y7wQVYffiHSYlVEfb-vaOfRKbe2UTkQR9gDhADDj13CleldZ2cDYVJhcs1xCmEixEsIkgvodf_FtxIVhnWSjzojcj0jBuklXvuLvC9ne99ARnmnl_AAQAA)

## Stack Panel Sizing

By default `StackPanels` contain a `Visual` with the following properties:

* WidthUnits = Absolute
* HeightUnits = RelativeToChildren

This means that as more children are added to a StackPanel, the StackPanel grows vertically.

The following code creates a main StackPanel with two internal StackPanels. Each internal StackPanel contains a Button which can be used to add labels to the respective internal StackPanel.

```csharp
// Initialize
var mainStackPanel = new StackPanel();
mainStackPanel.AddToRoot();
mainStackPanel.X = 50;
mainStackPanel.Y = 50;
mainStackPanel.Width = 200;

var firstInternalStackPanel = new StackPanel();
mainStackPanel.AddChild(firstInternalStackPanel);
var firstButton = new Button();
firstButton.Text = "Add to first stack panel";
firstButton.Width = 250;
firstInternalStackPanel.AddChild(firstButton);
firstButton.Click += (_, _) =>
{
    var label = new Label();
    label.Text = $"Added at {DateTime.Now}";
    firstInternalStackPanel.AddChild(label);
};

var secondInternalStackPanel = new StackPanel();
mainStackPanel.AddChild(secondInternalStackPanel);
var secondButton = new Button();
secondButton.Text = "Add to second stack panel";
secondButton.Width = 250;
secondInternalStackPanel.AddChild(secondButton);
secondButton.Click += (_, _) =>
{
    var label = new Label();
    label.Text = $"Added at {DateTime.Now}";
    secondInternalStackPanel.AddChild(label);
};
```

[Try on XnaFiddle.NET](https://xnafiddle.net/#snippet=H4sIAAAAAAAACr2R3UrDQBCF7wN5h2HxIsUSiuCNEkErSEFENKDCQlm7K11MdiWZWDHk3d3d2DQ_hiKCuUrmzJz5Jqf0PQCyyK-KlJwAZoWYuopUEiVL5KcwZfLOMkiZVPfIVq-3TIkEIlBiA7tCMDmlqtsTnnMe6zut8Sfx0Vgcz4b1p5H6g-S4NtrRzIpUWaYXmeW4UCgyxZLfw83XMuHBiIkdaXZcFIhaffvWH86zJYax-EDTQYlxBtT1IOTWEN6sIyW9ieYkd-8IRw-0Hu3vnifSbDmMIFhOYTmB6Iyqkiowj70hYc_NX7m27w7eqk7Zoh84dsGBIZSXDEUsUxHe6E3l0G3_XkhnaN2rJqVcrLTif41pzGWbU62PBdVWB0nV4iCqzkw3qzGYPu4urY7Zv8W1n7OVF_G9yve-AA6oIAUSBAAA)

<figure><img src="https://2695663588-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-M_fzQmxQ1VeUFHcoo2c%2Fuploads%2Fgit-blob-222c8b03facfe9cbbd43c54e60167a0992712da6%2F13_09%2051%2057.gif?alt=media" alt=""><figcaption></figcaption></figure>

## Orientation

StackPanel Orientation controls whether items in a StackPanel are positioned top-to-bottom or left-to-right. Changing the StackPanel Orientation property changes the internal visual's ChildrenLayout property. For more information on ChildrenLayout see the [ChildrenLayout page](/gum/gum-tool/gum-elements/container/children-layout.md).

WidthUnits and HeightUnits are not changed when changing Orientation. If you want the StackPanel instance to grow horizontally when changing Orientation to Horizontal, you need to modify the WidthUnits and HeightUnits.

The following code creates a horizontal StackPanel with buttons stacked left-to-right.

```csharp
// Initialize
var stackPanel = new StackPanel();
stackPanel.AddToRoot();
stackPanel.X = 50;
stackPanel.Y = 50;
stackPanel.Orientation = Orientation.Horizontal;
stackPanel.Visual.WidthUnits = Gum.DataTypes.DimensionUnitType.RelativeToChildren;
stackPanel.Visual.HeightUnits = Gum.DataTypes.DimensionUnitType.Absolute;
stackPanel.Height = 50;

for (int i = 0; i < 5; i++)
{
    var button = new Button();
    stackPanel.AddChild(button);
    button.Text = "Button " + i;
}
```

[Try on XnaFiddle.NET](https://xnafiddle.net/#snippet=H4sIAAAAAAAACo1QTU_DMAy9T9p_sHrqNBTtsguDw2AS4wQa5UvqJaOGWmQOatwBm_bfcVoNKNqBXJz3nv0Sv22_B5Bchot6lRyDVDUeNQwxCVlHG1Q6WdsKgtin12vL6OAUGN_h5ptIB5Ocf3QzLYrML7yXv8KDjo5HXe7xAHdVEbJYIc-q_kJm7ivaeEWuO3FHobbO3FMh5a3-Peic7mRmVmz2-YbBzGiFHNQjypEyC3RqusbMn5fkigr5oOcc6aWU_5pOl8G7WrBr1XrsN8352VeQEguQcqOJlhMYaxkOBzlvcwY9MfRlLdJkEAM_a0CTadS7gTcrpG3_vqNFJsOP-HSetAZ6gSGQ9uySfm_3BWmf8YcCAgAA)

## Children

StackPanel children can be directly accessed through its `Visual.Children` property.

For example, the following code shows how to randomize items in a StackPanel.

```csharp
// Initialize
StackPanel panel = new();
panel.AddToRoot();
panel.Anchor(Gum.Wireframe.Anchor.Center);

for(int i = 0; i < 10; i++)
{
    var text = new TextRuntime();
    panel.AddChild(text);
    text.Text = "Text " + i;
}

// now randomize them:
for(int i = 0; i < 10; i++)
{
    panel.Visual.Children.Move(i, System.Random.Shared.Next(10));
}
```

[Try on XnaFiddle.NET](https://xnafiddle.net/#snippet=H4sIAAAAAAAAA51Oy07DMBD8FcsnR4qstNxScaA5IA4glERwIBysektWJGvkR3lU-XfspCB6xQfv7Ozszhz5jbsOIy-9DZDz4JBeHC-feCTlI1rYWzUCf845EnpUA34BL_lBWfamCAZ2yQjeWePV7vU-ESLbdDSP5JXWramN8X852vXGirPrJ1JWQB5s0u6jBMkzjOeLTSxdKIqLiq1Sk_B6u_xZR8eOWHwpkYcPfwrURlgH8jjC7J4kv6mqHgctkvpnlLBsl_X58npuFriULcMonv4VbnF-QBfUIGd3CyRvzQEE5qz5dB5GWSvSZpRNryxoeRf9xarIUsKJT9_L8SvBqAEAAA)


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://docs.flatredball.com/gum/code/controls/stackpanel.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.