bug#71866: 30.0.50; [macOS] Cursor hiding char behind it with certain theme customization

[Dmitry Gutov <dmitry@gutov.dev>]

On 22/07/2024 19:02, Alan Third wrote:
> On Mon, Jul 22, 2024 at 04:27:30PM +0100, Alan Third wrote:
>>
>> AFAIK it's the only way of *drawing* the cursor, but it's certainly
>> possible that something else is *clearing* that space and not
>> redrawing the cursor. Unfortunately I've no idea what that might be.
> 
> FWIW, and apologies if you've already noticed this, but on my Mac I
> can see it drawing a white hollow box cursor on the second frame when
> the first frame is selected. I can see it overlapping some of the
> characters.

Not really - I've never seen what you've described. :-(

The artifact that I see only happens when the frame in question is the 
selected one.  When I switch to the frame, the character under cursor 
becomes blank. When I switch away, the character becomes visible again.

> Is it possible you're seeing a white box cursor with white text
> instead of a black box cursor with white text?

Perhaps if Emacs only uses the said "white box cursor" for the active 
frame only? And only when certain characters are under the cursor?

TBF in my custom config I see a more advanced version of this (many/most 
characters become blank under cursor after switching to some secondary 
frame) - but still that doesn't seem to happen in non-selected frames.

> A little git archaeology shows that the colour handling used to be a
> lot more complicated, but it was simplified some time ago. I don't
> understand what the old code was doing, and colour handling on the NS
> port was always a little different for some reason...