Dear Maintainer,

What led up to the situation? Unknown.

What exactly did you do (or not do) that was effective (or ineffective)? Did
fresh install on Virt-manager.

What was the outcome of this action? When I try to change the default theme I
get told it's not installed, but it gets applied.

What outcome did you expect instead? to change the theme to one of tje other
themes installed by default with no errors.

Hi,
I can confirm this. If we select any of the themes from upstream
`mate-themes` package, we can see that the change takes effect, but a warning message is displayed on the 'Theme' tab of MATE
'Appearance', saying, "This theme will not look as intended because
 the required GTK+ theme '<theme-name>' is not installed." And if
 we check the 'Controls' tab of 'Customize Theme', it either does not
 show any control for that theme (e.g., Menta) or it shows with a
question-mark (e.g., Black MATE). Please see attached screenshots.

This is an unfortunate side-effect of the fix for the bug #1092596.
 It removes the 'gtk-2.0' directory from all of the themes. It seemsthese are required. Adding back the (corresponding) 'gtk-2.0'
 directories fixes this warning.

As much as I understand, we are still good with bug #1092596 as
 no gtk2-engines are required to be installed/present on the system.

```
sv@sid-vm:~$ dpkg -l | grep gtk2
sv@sid-vm:~$ 
```