PDFs and documents
Documents are not web pages, and every editor keeps its text somewhere different. Readalix handles the five that matter, with one quirk each worth knowing.
Chrome PDFs
Open a PDF in Chrome's own viewer and press play with nothing selected: it reads the whole document from the top. Select first, and it reads only the selection.
The highlight here is drawn by the viewer itself rather than painted over it, so it stays exact through zooming, scrolling and rotating. Scanned PDFs work too, as long as the viewer can find text in them.
Two differences from an ordinary page: the element picker is not offered, since a rendered PDF has no elements to pick, and clicking the document stops the read exactly as clicking a page does.
A PDF you are only previewing is read the same way: an attachment open in Gmail, a file previewed in Google Drive, a document opened from a OneDrive or SharePoint file list. There is no need to download it first.

Google Docs
Docs draws its text on a canvas, which is why most read-aloud tools go quiet there. Readalix reaches into the editor and reads it, with the sentence tint and the word highlight painted over the canvas.
Press play with nothing selected and it reads the whole document from the top. Select a passage and it reads that. The element picker works here as well, when you press the pick button yourself.

Word Online
Word for the web reads from a selection: choose the text you want, then press play. Use Ctrl+A inside the document if you want the lot.

PowerPoint Online
Press play and it reads the slide you are on, title and body together. Move to the next slide and press play again.

Google Slides
Same as PowerPoint: the slide you are looking at is the slide that gets read, with the highlight painted over the deck.

At a glance
| Surface | Play with nothing selected | Element picker |
|---|---|---|
| Web page | Reads the article it detects | Yes |
| Chrome PDF | Reads the whole document from the top | No |
| Google Docs | Reads the whole document from the top | Yes |
| Word Online | Asks you to select first | No |
| PowerPoint Online | Reads the current slide | No |
| Google Slides | Reads the current slide | No |