Many weird behaviours with text selection

[hhmmjjnn]

The Rich Text demo have many weird behaviours with text selection when:

1. Triple-clicking
2. Dragging the mouse vertically
3. Shift+Up/Down
4. Resizing the viewport
5. Zooming the viewport

You can try all these 5 actions with the non-pretext paragraph at the top, then with the pretext-enabled paragraph below, and notice the inconsistencies. Also, compare all that to the pdf.js demo.

Links:

• https://chenglou.me/pretext/rich-note/
• https://mozilla.github.io/pdf.js/web/viewer.html

[hhmmjjnn]

Action 1: Triple-clicking

HTML/CSS behaviour: the paragraph is entirely selected
pretext behaviour: the fragment is entirely selected
pdf.js behaviour: the fragment is entirely selected

20260420-1959-43.2057762.mp4

[hhmmjjnn]

Action 2: Dragging the mouse vertically

HTML/CSS behaviour: very smooth and stable
pretext behaviour: stutters predictably
pdf.js behaviour: mostly smooth, with some sporadic stuttering

20260420-2009-29.2571290.mp4

20260420-2010-22.0631579.mp4

[hhmmjjnn]

Action 3: Shift+Up/Down

HTML/CSS behaviour: the next/previous line is selected up to the horizontal position of the text cursor
pretext behaviour: the selection advances/retracts to some arbitrary stop, with no logic apparent to me
pdf.js behaviour: very similar to the HTML/CSS behaviour, with some subtle quirks

20260420-2028-32.6246918.mp4

[hhmmjjnn]

Actions 4 and 5: Resizing and zooming the viewport

HTML/CSS behaviour: text selection is not affected by viewport resizing and zooming
pretext behaviour: when the viewport is resized or zoomed, the pretext-enabled paragraphs are deselected
pdf.js behaviour: when the viewport is zoomed, the selection flickers for one or two seconds

20260420-2039-42.1683413.mp4

[hhmmjjnn]

Ideally, there should be a WHATWG standard to tell the browser "hey, this is a line" and "that is a paragraph."