Gum gum-tool-dialogs

Reference guide for Gum's dialog/popup systems. Load this when working on dialog windows, DialogService, DialogWindow, DeleteOptionsWindow, dialog scrolling, dialog layout, or adding new dialog types.

install

source · Clone the upstream repo

git clone https://github.com/vchelaru/Gum

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/vchelaru/Gum "$T" && mkdir -p ~/.claude/skills && cp -r "$T/.claude/skills/gum-tool-dialogs" ~/.claude/skills/vchelaru-gum-gum-tool-dialogs && rm -rf "$T"

manifest: .claude/skills/gum-tool-dialogs/SKILL.md

Gum Dialog Systems Reference

Two Separate Systems

Gum has two independent dialog systems. Knowing which one is involved is critical before making changes.

1. DialogService System (MVVM, most dialogs)

Used by: message popups, yes/no confirmations, text input, choice selection, plugin management, import dialogs.

Flow:

DialogService

creates a

DialogWindow

, sets its

DataContext

to a view model. The

Dialog

control inside uses a

DialogTemplateSelector

to resolve the view model type to a

UserControl

view. After the view loads,

Dialog.OnContentChanged

binds attached properties from the view up to the

Dialog

control via deferred dispatch (

DispatcherPriority.Loaded

Key attached properties on views (set in XAML on the UserControl):

```
Dialog.DialogTitle
```
— window title
```
Dialog.Actions
```
— custom button area (replaces default OK/Cancel)
```
Dialog.AuxiliaryActions
```
— extra buttons on the left side (e.g. Browse)
```
Dialog.ScrollContent
```
—
```
true
```
(default) enables outer ScrollViewer;
```
false
```
disables it so the view can manage its own scrolling (used by ImportFromGumxView)

View resolution:

DialogViewResolver

maps view model types to views by naming convention (

FooViewModel

FooView

) or by

[Dialog(typeof(VM))]

attribute. Scans assemblies lazily and caches results.

Window sizing:

DialogWindow

starts with

SizeToContent="WidthAndHeight"

. After content loads,

Dialog.OnContentChanged

switches to

SizeToContent.Manual

and clears the view's fixed Width/Height (sets to NaN), allowing the window to be resizable.

DialogService.CreateDialogWindow

sets

MaxHeight

to the owner window's

ActualHeight

2. DeleteOptionsWindow (standalone, code-behind)

Used by: delete confirmation only (

DeleteLogic.ShowDeleteDialog

Why it exists separately: The delete dialog needs runtime UI composition — plugins inject checkboxes and options into a

StackPanel

(e.g., "Delete associated files?", "Remove child instances?"). This cannot be done through the MVVM template system.

Flow:

DeleteLogic

creates a

DeleteOptionsWindow

directly, sets

Message

and

Title

properties, calls

PluginManager.ShowDeleteDialog()

(which lets plugins add controls to

MainStackPanel

), then calls

ShowDialog()

Not managed by DialogService — no view model, no template selection, no attached property binding. Changes to

DialogWindow.xaml

Dialog.cs

have zero effect on this window.

Key Files

File	System	Purpose
`Gum/Services/Dialogs/DialogService.cs`	MVVM	Creates and shows DialogWindow instances
`Gum/Services/Dialogs/DialogWindow.xaml`	MVVM	Window chrome, layout template with ScrollViewer + button footer
`Gum/Services/Dialogs/Dialog.cs`	MVVM	ContentControl with attached properties and template selector
`Gum/Services/Dialogs/DialogViewResolver.cs`	MVVM	Maps view model types to view types
`Gum/Services/Dialogs/DialogViewModel.cs`	MVVM	Base class with affirm/negative commands and RequestClose event
`Gum/Gui/Windows/DeleteOptionsWindow.xaml`	Standalone	Delete confirmation window layout
`Gum/Gui/Windows/DeleteOptionsWindow.xaml.cs`	Standalone	Code-behind with plugin-accessible StackPanel
`Gum/Managers/DeleteLogic.cs`	Standalone	Creates and shows DeleteOptionsWindow (line ~227)

Common Pitfalls

Wrong system: The most common mistake is modifying

DialogWindow.xaml

Dialog.cs

expecting it to affect the delete dialog. Always verify which system shows the dialog you're fixing.

ScrollViewer behavior: The

Dialog

template wraps content in a ScrollViewer. With

Auto

scrolling, child controls get infinite available height during WPF measure — so internal scroll viewers (like a TreeView) won't scroll. Set

Dialog.ScrollContent="False"

on views that need bounded height for internal scrolling.

Deferred binding:

Dialog.OnContentChanged

binds attached properties at

DispatcherPriority.Loaded

, not immediately. Code that reads these values before the dispatch fires will see defaults.