A box that starts its paragraph was a trap: there is no text position beside
it, so the browser pulled the caret meant for the box's own place in the line
into the frame and everything typed there landed inside it.
A frame nobody is editing is now an atom to the browser — a contenteditable
node decoration, dropped while the caret is in its text, the frame placing the
caret itself on the click that enters it. ArrowLeft/ArrowRight at the box's
first and last text position step out to it. The decoration walk enters blocks,
without which it never reached an inline box at all.
Steffen Becker
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