mdWorX

A Markdown viewer and editor that runs inside Directory Opus, in the viewer pane or popped out into its own window.

I built this because I work with a lot of Markdown files day to day and didn't want to fire up another app every time I needed a small edit. The existing DOpus options kept throwing errors for me, partly because of a WebView2 DPI bug they don't work around, so I rolled my own. It's a solo project, shared in case it's useful to anyone else.

How it works

There are three views, switched from the top toolbar:

• Reading for clean rendered HTML. The formatting toolbar is hidden in this mode.
• Live keeps the formatting visible until your cursor enters a line, at which point the raw markdown markers reveal themselves for that line only. Click somewhere else and they hide again.
• Source for raw Markdown. Click Source a second time to split the pane (see below).

Double-click an .md file and the viewer pops out into its own window. Same modes, same split view, just without the DOpus chrome around it. The pop-out window keeps unsaved edits if you switch focus to DOpus and come back; the in-pane viewer reloads when you click a different file, so save first.

Split preview in Source mode

Click Source a second time while already in Source mode and the pane splits in two: raw markdown on the left, live-rendered preview on the right. Click Source a third time to close the split and return to single-pane Source.

• Drag the centre handle to resize the two panes. The split position is remembered for the session.
• Linked scrolling is on by default. Scrolling either side scrolls the other to the matching position, so the preview tracks the source as you write. The link icon sits in the middle of the split handle.
• Click the link icon to unlink the two panes. Each side then scrolls independently — handy when you want to read one section in the preview while editing somewhere else in the source. Click again to re-link; the panes resync from the active side.
• Both panes use the same word-wrap setting. Toggling word wrap in the top toolbar applies to source and preview together.
• The editing toolbar stays available at the bottom in split mode and acts on the source pane.

Toolbars

Top toolbar (always visible):

• Reading / Live / Source mode buttons
• Save and Save As
• Word-wrap toggle for code blocks and long URLs
• Settings (opens the settings dialog)

Editing toolbar (visible in Live and Source modes):

• Bold, italic, strikethrough, inline code, link, footnote
• H1 / H2 / H3
• Bulleted list, numbered list, task list
• Outdent / indent
• Blockquote, fenced code block, image insert

The image button opens a small popup: pick a file with Browse... (or paste a URL or relative path), set alt text, optional width and height in px, and an alignment (none / left / centre / right). Tick Copy file to this document's folder and the picker copies the chosen file next to the markdown and inserts a relative path, so the document stays portable.

Image dimensions and alignment ride along in the alt-text using Obsidian-compatible syntax: ![alt|640](path) for width, ![alt|400x300](path) for width and height, ![alt|400x300|center](path) for both plus alignment. Files rendered through this syntax round-trip with Obsidian and other editors that read it.

What it renders

GitHub-flavoured Markdown plus footnotes, definition lists, abbreviations, highlights (==text==), subscript (H~2~O), superscript (E=mc^2^), task lists (clickable in Live mode), autolinks, and emoji shortcodes. Code blocks are syntax-highlighted by Shiki and have a copy button in the corner that flashes green to confirm. Footnote definitions at the bottom of the document are editable in place: click the text and start typing.

Settings

The Settings dialog (gear icon in the top toolbar) covers every visual option without you having to hand-edit a JSON file. Every field has a hover tooltip, the colour preview repaints live as you scroll through palettes, and the dialog itself follows whatever palette is active.

Empty fields mean "use the theme default" — leave a field blank and the active palette decides. Reset all fields blanks the form back to defaults, but nothing applies until you click Apply. Apply pushes the settings to every open viewer pane at once.

What it covers:

• Theme and preset picker — 29 built-in palettes (17 dark, 12 light — see docs/palettes.md for the visual reference) plus any custom entries you've saved. Picker grouped Light / Dark / Your themes.
• Save menu — capture the current state three ways: Save as palette keeps just the colours, Save as style keeps just typography and layout (fonts, weights, sizes, line-heights, padding, max-width), Save as theme bundles everything. Saved entries appear in the picker alongside the built-ins; your own can be deleted, built-ins can't.
• Document handling — encoding (auto, utf-8, utf-16 / -le / -be, system, the cp1250–cp1258 family, ISO-8859 single-byte, Shift-JIS, GBK, Big5, EUC-KR, KOI8-R / -U), fallback encoding for when auto-detection fails, "render single newlines as line breaks" (hard line breaks), and "show formatting characters in Live mode" (overlays every space, tab, and line ending; LF and CRLF lines get distinct badges).
• Page surface — background, border colour and thickness, drop-shadow depth (none through floating), body text colour.
• Rules and dividers — horizontal-rule colour and thickness, heading underline colour, thickness, and style (solid, gradient, or none). Heading underline thickness is independent of HR thickness, so a thin rule with a chunky H1 underline (or vice-versa) works fine. Default style is gradient.
• Per-level heading colours — H1 through H6, each independent.
• Body and code typography — font family, weight, size, line-height for body prose and for code blocks. Highlight font weight is its own field so ==marked== text can be bolder than surrounding prose without affecting bold elsewhere.
• Inline accents — per-element colours for bold, italic, strikethrough, inline code, highlight (background plus foreground plus opacity), and links. Each follows the active palette by default; pin a specific colour to override.
• Layout — content max-width and page padding.

Palettes

29 preset palettes ship with mdWorX: 17 dark, 12 light. The full visual reference is in docs/palettes.md with side-by-side rendered samples.

Light palette	Dark palette

Built-in dark: Default Dark, Dracula, Solarized Dark, Nord, Gruvbox Dark, One Dark, Tokyo Night, Ayu Dark, Catppuccin Mocha, GitHub Dark, Obsidianite, PLN Dark, AnuPpuccin Frappé, Everforest, Rosé Pine, Vesper, Red Rascal.

Built-in light: Default Light, PLN Light, Solarized Light, GitHub Light, Ayu Light, Gruvbox Light, Catppuccin Latte, One Light, Tokyo Night Day, Nord Light, Alucard, Obsidianite Light.

Default Auto follows the DOpus viewer-pane background and picks Default Dark or Default Light to match. Picking any preset re-tints toolbars, links, selection, syntax highlights, and scrollbars to fit.

Encoding

Files that aren't UTF-8 still open cleanly. UTF-8 and UTF-16 (LE/BE) are detected from the file's header bytes automatically. For older codepages you pick the fallback in the settings: Shift-JIS for Japanese, GBK for Simplified Chinese, Big5 for Traditional Chinese, EUC-KR for Korean, CP1250 to CP1258 for the various European Windows codepages, ISO-8859-1/2/15, KOI8-R/U for Cyrillic, or your system default. Right-to-left scripts (Arabic, Hebrew), joining scripts (Devanagari), and mixed scripts on the same line all render correctly. Saving writes back as UTF-8; if you opened a file in a legacy encoding, use Save As to keep the original.

The repo ships with test fixtures covering each script and encoding.

Install

1. Quit Directory Opus.
2. Download mdWorX_vX.Y.Z.zip from the Releases page and extract it anywhere.
3. Double-click Install.cmd and accept the UAC prompt.
4. DOpus relaunches and Markdown files open in mdWorX.

To remove it, double-click Uninstall.cmd from the same folder.

Manual install

If you'd rather not run the script, extract the zip contents into C:\Program Files\GPSoftware\Directory Opus\Viewers\ (admin rights needed). The end state is:

Viewers\mdWorX.dll
Viewers\mdWorX_assets\

User settings live at %APPDATA%\HyperWorX\mdWorX\settings.json; saved custom themes live in %APPDATA%\HyperWorX\mdWorX\themes\. The DOpus uninstall script leaves your settings folder alone — delete it by hand if you want a clean wipe.

Requirements

• Windows 10 or 11, x64
• Directory Opus 12 or later, 64-bit
• Microsoft Edge WebView2 Runtime (preinstalled on Windows 11; download for Windows 10)

Tips

• In Source mode, click Source again to toggle the split preview. Drag the handle to resize; click the link icon in the middle of the handle to unlink scrolling.
• The disk icons save the file. The icon next to them toggles word wrap on code blocks and long URLs.
• Click the copy button in the corner of any rendered code block to copy the snippet.
• In the viewer pane: save before clicking off to another file. If you switch files without saving, the pane reloads with the new selection and unsaved edits are gone. The pop-out window doesn't have this problem (you can edit, click around DOpus, come back, and save).

Building from source

cd web
npm install
npm run build

cd ../plugin
.\build.ps1

The DLL ends up in build-out\Release\ and the web assets in build-out\mdWorX_assets\. See docs/dev-setup.md for the full toolchain setup, including the DOpus viewer plugin SDK.

Licence

MIT. © 2026 HyperWorX.