PJ-Singh-001
commented
3 years ago I found which icon is used. It is named preferences-ubuntu-panel-symbolic.svg.
ISSUE
Icon themes that support light and dark window themes have their own version of the preferences-ubuntu-panel-symbolic.svg icon.
However, Newaita inherits from breeze, gnome, and hicolor themes, so there is no "working" version of the preferences-ubuntu-panel-symbolic.svg icon that Newaita can fall back to.
The hicolor theme has the following icon:
(hicolor/scalable/apps/preferences-ubuntu-panel-symbolic.svg)
Unfortunately, the hicolor version of this icon does not render completely when the a light colored window theme is selected. In a light colored window theme, you can not see the display monitor, just the eye portion of the icon.
This is not an issue with the hicolor icon theme, because it is not designed to adapt to light and dark window themes.
WORKING EXAMPLE
For example, the Yaru theme has the following icon:
(Yaru/scalable/categories/preferences-ubuntu-panel-symbolic.svg)
This icon does render completely for both light and dark colored window themes. You can see the display monitor and the eye portions of the icon.
SOLUTION
Newaita needs its own icon named preferences-ubuntu-panel-symbolic.svg.
This icon should be placed in Newaita/categories/scalable/preferences-ubuntu-panel-symbolic.svg (I think).
In the latest version of Newaita (1.09.20a), the "Light" version of the "Appearance" icon used in the left pane of Ubuntu 21.04's System Settings has an issue.
Only the central portion (the "eye") of the icon is visible. The rest of the icon (the "display monitor" portion) is not visible.
This affects the light version of Newaita...
The dark version of this icon looks OK...