It's a subtle issue so I did a screencap to make it clear. This is what is happening:
This is what I expected to happen:
That was with the Ambiant-Mate-Dark theme and the icons from Ubuntu-Mono-Dark. Not sure if this is the right place to report this or not but I wanted to mention it in case it was possible to get this fixed before the next release of the theme.
@bornagainpenguin it is not exactly 'cursor' you are talking about but rather the icon for file, between normal view and when renaming it, correct? When renaming in Yaru-MATE Dark, icon becomes dark as well. It doesn't have that green tint. Did I understand correctly? See pics below...
Ambiant-MATE dark theme
vs
Yaru-MATE Dark theme
I found the same in 'Greybird-dark' theme.
And also, High-contrast-inverse theme.
When selected,
when renaming,
But BlackMATE is OK.
I think @bornagainpenguin means the blinking cursor when editing the text :
I have the same issue, but this looks related to my theme on 20.04 :
(the blinking cursor is not visible when Im trying to edit the file name)
A workaround is to add a background to the cursor in css config of your theme (source here) :
.caja-desktop.view .entry,
.caja-navigation-window .view .entry {
caret-color: #000;
}
The cursor is visible now in dark theme :
it is not exactly 'cursor' you are talking about but rather the icon for file, between normal view and when renaming it, correct?
Icon? Now what's wrong with the icons? No, the other poster got it exactly correct:
I think @bornagainpenguin means the blinking cursor when editing the text
This is a problem. I can't think of any circumstances that you may want things to behave this way. It completely breaks usability. It is impossible to know where you are in the file name to do any editing or renaming. If the them somehow makes it out to the 22.04 LTS it's going to create a horrible impression.
Thankfully it appears fixable:
A workaround is to add a background to the cursor in css config of your theme
I'll give this a shot as soon as I can get to the laptop again. Thanks!
But this needs to be fixed. It looks horrible.
Only someone that got this issue can understand it 
@saivinob was trying to help 
@olek, brilliant! Thank you for correcting me and for the workaround. It works here.
Now I see the same issue with 'Kate' color scheme for pluma but chances of somebody using that color scheme under Yaru-MATE-dark theme is probably next to nothing.
@bornagainpenguin, for Yaru-MATE-dark, I had to change two files 'gtk.css' and 'gtk-dark.css' under /usr/share/themes/Yaru-MATE-dark/gtk-3.20/. Changes under /usr/share/themes/Yaru-MATE-dark/gtk-3.0/ did not work.
Don't be so sure! 
The best papercuts fixed are ones that 'nobody' will ever encounter. Because then when someone switches to a different distro they're shocked when they run into something like this that was working just fine on Ubuntu-Mate. Conversely encountering something like this in a LTS is like a slap in the face because if something so basic as a system theme is broken, what else did they miss?
The fact that Ubuntu (and now Ubuntu-Mate) are so good about fixing things like this are part of why I love the distro so much. It makes for a very polished end-user experience.
No, I realize that. It's part of the reason I included the screencaps because it's a very visual thing. I appreciate that @saivinob was trying to help. I didn't mean anything by my response, I was going for faux exasperated: if it ain't one thing, it's two things. That kind of thing.
@bornagainpenguin, I have raised bug for this issue (LP: #1926094). Please mark as 'affects me' and add your observations as needed.
@olek, I have taken liberty to post your workaround. If you have anything to add (/correct) please do so.
Thank you both.
Thanks! I've added myself to the bug report so hopefully this will get fixed sooner than later for everyone.
I wonder if it's worth it to check against the other default themes to ensure this is not an issue going forward for any of those?
