Return to the start screen? Parts aren't saved with the document.
Drop a PDF on the start screen, use Open PDF…, or paste a link with Open URL…. Recently opened documents are listed on the start screen — click one to reopen it.
A part is a named selection of pages that becomes its own PDF. Click pages to toggle them in the active part; Shift-click selects a range. A page can belong to several parts at once, and parts don't need to be contiguous. Drag the ⋮⋮ handle to reorder parts — the single-PDF export follows list order.
Type in the search box, then Enter / Shift+Enter to step through matching pages. Double-click any page to open the scrolling reader — its shortcuts are listed in the reader's own toolbar.
Choose One PDF per part, One PDF (with parts in list order), or both, optionally set a base name, then Build PDF(s). Files go to Downloads unless you pick an output folder — or tick Ask where to save each file instead for a per-file Save As dialog. The Files panel gives you From/To folder panes for browsing sources and destinations directly.
Textmill is one self-contained file — save it as textmill.html and it works offline from your own disk, no server needed.
Found a bug or have an idea? Leave me a note — this opens your mail app with a pre-addressed message.
Full disclosure: this app is vibe-coded — written almost entirely by Claude (Anthropic), directed and tested by a human. All the more reason to report anything odd.
Forget the saved output folder (exports go back to your Downloads folder), clear the list of recently opened documents, and re-arm the one-time hint bubbles. This only clears Textmill's memory — your actual files are never touched.