Transparency in Fringes for Blocks

[adimit]

Given the following minimal config:

(package-initialize)
(menu-bar-mode -1)
(tool-bar-mode -1)
(scroll-bar-mode -1)
(load-theme 'modus-vivendi)
(add-to-list 'default-frame-alist '(alpha-background . 10))
(use-package org-modern
  :ensure t
  :config
  (global-org-modern-mode))

and a recent Emacs compiled for transparency (That'd be Emacs 29—on Wayland, you'll need PGTK enabled), org blocks have a fringe with a solid background:

Note how the rest of the fringe does have a slightly different background, but it's still transparent.

Transparent fringes are possible, though I'm not sure if that works with custom bitmaps. Here's an example of an edebug session with a transparent breakpoint indicator:

I tried solving the issue on my own, but I'm stuck. I tried defining a different face for the fringe than org-block-begin-line, but even when I left out the :background completely, it still showed.

The only workaround I found is to redefine the custom fringe-bitmaps to have width 1. Then only the actual line is shown and the rest of the fringe remains transparent. Of course, we miss out on the pretty corners.

Thanks for org-modern, I really love it :)

[minad]

Thanks. I don't use Pgtk and Wayland so I cannot easily debug this myself. It could be that this is a Pgtk problem.

Fringe bitmaps are bitmaps, so I think the definitions should not make much of a difference. You can compare the fringe bitmap definitions here:

org-modern/org-modern.el

Lines 633 to 638 in 2ab56bd

	(define-fringe-bitmap 'org-modern--block-inner
	(vector v) nil 16 '(top t))
	(define-fringe-bitmap 'org-modern--block-begin
	(vconcat (make-vector g 0) (vector w) (make-vector (- 127 g) v)) nil 16 'top)
	(define-fringe-bitmap 'org-modern--block-end
	(vconcat (make-vector (- 127 h) v) (vector w) (make-vector h 0)) nil 16 'bottom))))

and in Edebug: https://github.com/emacs-mirror/emacs/blob/647cecc853e53a3be0bb2cf5328cd19e677217c9/lisp/emacs-lisp/edebug.el#L3197-L3198

Looking at the face definitions seems to be the correct approach. Maybe try a different face like edebug-enabled-breakpoint? See Edebug: https://github.com/emacs-mirror/emacs/blob/647cecc853e53a3be0bb2cf5328cd19e677217c9/lisp/emacs-lisp/edebug.el#L3228

It could also be that the wrap-prefix we use in Org-modern exposes a bug in Emacs itself. As you see, in Edebug, the fringe bitmap is added to an overlay, while we add it to a wrap-prefix. Maybe this is the issue? You could check this by using the edebug-breakpoint bitmap and edebug-enabled-breakpoint face in Org-modern. Is the fringe transparent if you do that?

[minad]

Okay, thanks for reporting back! Then this is an issue in Emacs itself and should be reported there via M-x report-emacs-bug ideally with a small code snippet demonstrating the issue and the difference of overlays and wrap-prefix or line-prefix.

[adimit]

Okay, I'll try to distill this into something actionable and file it as a bug.

Apropos of nothing, timestamps exhibit the same problems, it seems.

The black border goes away on hover with the mouse pointer.

[adimit]

Should anyone be curious, here's the bug report on the emacs-bugs list.

[adimit]

The bug has been fixed and should be part of the next Emacs release. (Emacs 30)