Distracting brightness "pulsing" with multi-tab windows when not selected

[dancrossnyc]

I'm afraid I lack the vocabulary to adequately describe this issue, so I apologize for the verbosity of this report; please bear with me. This has been happening for some time now, so it's not a new problem. I'm using the version built form nightly commits; currently I'm at 4eb5885 running on a Mac.

Suppose I create a Ghostty window, and in that window, split the window vertically. In one of the splits, I run some program that uses escape sequences to set colors, such as helix on some file that uses syntax highlighting. I then focus on the other pane, not running that program, and then change focus to some other window (such as the web browser window that I am typing this in).

Then If I look at the unselected, unfocused, pane in the Ghostty window, I will observe it seem to "pulse" as it cycles through several levels of brightness; it will progressively dim in stepped intervals at a rate of, maybe, two or three times a second until it hits some lower limit, and then pop back to full brightness; repeating continually. This can be very distracting, particularly since it often happens when the window is in one's peripheral vision.

Again, I apologize for the vagueness of this description; I'm attaching a video, taken with my phone, to this issue to try and illustrate what I mean. Searches for "brightness" and "dimming" didn't show anything that struck me as a dup, so additional apologies if this is a known issue.

GhosttyDimmingBrightness.mov

[taylrfnt]

I cannot reproduce this on tip - OP, can you please share the OS you're running on?

Edit: Missed the tag, I see it's MacOS

[taylrfnt]

Do you see this when inside a tui like vim or persistently across all Ghostty surfaces?

[dancrossnyc]

I see it on any window that uses any text attribute; for example, if I run man ls in a split, and section names are bolded, then the artifact appears and seems to remain, even after the program that does that has exited.

For instance, at the moment I have a window with two splits; both are only displaying the shell prompt, which uses no special visual effects, and the pulsing effect is evident in one.

[mitchellh]

Unfortunately after 2 months we haven't found any repeat way to see this behavior and no one else has chimed in that this is happening to them as well. For the sake of avoiding stale issues we're trying to triage, I'm going to close this, but if you or anyone else gathers more information, we'd love to learn more and try to fix this. Thank you.

[dancrossnyc]

I understand.

Just a thought; could it have something to do with whether "Secure Keyboard Entry" is enabled?

[mitchellh]

Unsure, does disabling it cause this to stop? It could potentially be related to the animation icon that shows up. You can disable that with macos-secure-input-indication = false if you want to see.

[dancrossnyc]

So a couple of data points here, and I owe an apology for not mentioning this earlier (truthfully, it just slipped off my radar).

Yes, disabling secure keyboard entry causes the effect to stop. For the record, I hadn't turned it on for any specific purpose other than, "secure keyboard entry sounds like a generally good idea...". If I turn it back on, the effect reappears. Using that setting you mentioned above (macos-secure-input-indication = false) to disable the animated indicator causes the effect to go away again.

This suggests to me that the effect is indeed related to the animation.