[konsole] [Bug 403729] New: Proper BiDi support
bugzilla_noreply at kde.org
Tue Jan 29 11:27:34 GMT 2019
Bug ID: 403729
Summary: Proper BiDi support
Assignee: konsole-devel at kde.org
Reporter: egmont at gmail.com
Target Milestone: ---
Konsole's BiDi suffers from several problems. (Apparently all it does is passes
continuous runs of identical attributes to some BiDi-aware font rendering.
There's much more to BiDi than this.)
Here's some of the problems (the list is not complete):
- It unconditionally applies the BiDi algorithm on the contents. This makes it
literally, mathematically provably impossible to have proper BiDi-aware text
viewers/editors on top of such a platform. (You can disable BiDi in the
settings, but having to do so every time one enters or leaves a text editor is
an unacceptable user experience.)
- It applies BiDi on lines of text, rather than paragraphs as the BiDi
- Upon every change of text attributes, it starts over the BiDi algorithm. That
is, e.g. the output of a "grep" which colors the match doesn't show up
- Also a side effect of the latter: text highlighting experience is terrible,
the characters move around as you highlight with the mouse.
- There's no support for overall right alignment (bug 401185).
I've spent a couple of months studying the topic, and came up with a first
draft proposal for the desired behavior, available at
I'm inviting you to join the discussion of the proposal if you have any
comments, and asking you to implement BiDi according to that proposal.
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