WinForms property reference

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All members are in CODE.Editor.WinForms. TextEditor is a sealed UserControl. The following tables cover its editor-specific properties; ordinary inherited WinForms layout properties such as Dock, Size, and Visible retain their normal meanings.

State and initialization

LocalImageOrigin is a public constant: https://code-editor-assets.example. Mapping a folder does not save images; provide an import event handler. Set pre-initialization properties before adding/showing the control if that could create its handle.

Document and view

These settings are available both directly on the control and on Options.

Setting Format to PlainText forces Source; RichJson forces Visual. Incompatible explicit ViewMode assignments throw. To load a new document atomically with format/view/language, use LoadAsync. To convert an existing document, use ConvertFormatAsync.

Presentation and preview

Display fonts do not change document formatting. Use content-formatting methods for stored rich styles. PreviewCss is separate from both. When the user resizes the divider, PreviewSplit is updated and PreviewResized fires.

Policy and image settings

Collection settings on Options

These do not have additional direct TextEditor forwarding properties:

Array getters return copies. Reassign an edited array rather than modifying a retrieved array and expecting live updates. Features is the override set; GetCapabilitiesAsync returns the effective policy after preset and format restrictions.

Update semantics

Use the owning UI thread. Settings changed before initialization form startup configuration; later changes are sent through the operation queue. Local range/enum checks throw synchronously, while browser policy/configuration checks may fail asynchronously and report through EditorError. A property can therefore hold a requested setting that the browser has not yet accepted. FlushAsync helps await queued work, and capability/snapshot queries establish accepted state.

Avoid a sequence of temporarily incompatible policy settings on a loaded document. Configure before loading where possible. Policy changes reset undo/redo. Empty DisplayFontFamily, Placeholder, and AccessibleLabel values clear the corresponding browser display override.

Options.MaxDocumentLength defaults to 0 (unlimited). Options.HistoryLimitBytes defaults to 33,554,432 (estimated snapshot budget; 0 disables it). Options.UnlockImageAspectRatio defaults to false. EditorLanguage exposes 195 catalog entries: 193 bundled highlight.js grammars, VisualFoxPro, and separate HTML/XML selections sharing a grammar. See chapter 20.

Options.UITheme is an EditorUITheme record with Palette, Variables and Css. It works before initialization and can be replaced at runtime. This styles the editing UI and its portals, separately from PreviewCss and stored content formatting. Styling guide.

Options.UIStrings accepts EditorUIStrings(Locale, Values) for shared UI wording and native search. Assign a new record to notify the control. See UI wording and localization.

Appearance (also Options.Appearance) is an expandable group of native color, font and spacing overrides. Nested changes apply live. See host appearance settings for the full property list and Olympus theme mapping example. ImageToolbar / Options.ImageToolbar accepts EditorImageToolbarOptions to configure Size, Replace, AlternativeText, Actions and InlineActions in Visual image toolbars. See image toolbar configuration. Image colors are exposed through Appearance.ImageToolbarBackground, ImageToolbarForeground, hover/pressed background and foreground, ImageSelectionColor, ImageSizeBackground and ImageSizeForeground.

Native spellcheck

SpellCheck (default true) is available on both TextEditor and Options and can change at runtime. It enables the Edge/Windows spell checker for prose and excludes code snippets, inline code, and programming-language Source views.

TextEditor.SpellCheckLanguage (default empty, runtime language) must be set before initializing or showing the control. WebView2 chooses its native proofing language at environment startup; changing the HTML language alone does not reliably change its dictionary. Use a new control/environment to choose another native language. Examples include English (en-US, en-GB), German (de-DE), Spanish (es-ES), French (fr-FR), Italian (it-IT), Dutch (nl-NL), and Portuguese (pt-PT); dictionary availability depends on Edge/Windows and installed language support.

var editor = new TextEditor {
    Dock = DockStyle.Fill,
    SpellCheckLanguage = "de-DE",
    SpellCheck = true
};
Controls.Add(editor);

Default profile folders are separated by explicit language so controls using different environment languages do not conflict. When specifying UserDataFolder yourself, use distinct folders for different environment languages. Added words are stored by Edge/Windows in its profile/dictionary, not in the document or review sidecar. The editor does not maintain dictionaries.

Right-click a misspelled word for Edge's native corrections and available dictionary/ignore commands. The native menu also keeps basic editing commands. Inspect remains available only while a debugger is attached; spelling works in release builds. Some native dictionary commands differ by runtime/OS. There is no custom hover spelling UI.

Preview splitter colors and runtime themes

Use editor.Appearance.PreviewSplitterBackground, PreviewSplitterForeground (grip), PreviewSplitterHoverBackground, PreviewSplitterHoverForeground, PreviewSplitterActiveBackground, PreviewSplitterActiveForeground (dragging), and PreviewSplitterFocusColor (outline). All are System.Drawing.Color properties; Color.Empty restores defaults.

All Appearance properties, including existing syntax and toolbar colors, update automatically at runtime. Set them in the host theme-change handler. FlushAsync() is only needed when subsequent code must wait for the WebView to finish applying changes.

// Apply again whenever the host theme changes.
editor.Appearance.PreviewSplitterBackground = Color.FromArgb(40, 40, 40);
editor.Appearance.PreviewSplitterForeground = Color.Silver;
editor.Appearance.PreviewSplitterHoverBackground = Color.DimGray;
editor.Appearance.PreviewSplitterActiveBackground = Color.SteelBlue;
editor.Appearance.PreviewSplitterFocusColor = Color.CornflowerBlue;

The MaximumEditWidth and MaximumPreviewWidth properties default to 900 logical (CSS) pixels and accept positive integers. RestrictMaximumEditWidth and RestrictMaximumPreviewWidth default to true; disable either independently to use the full available pane width. Content is centered when the pane is wider than its limit and shrinks to fit smaller panes. The edit limit applies to Visual and Source modes; WordWrap = false still allows long source lines to scroll horizontally. These settings affect display only, not saved content.