icons in iconsets that are completely white are not visible on the white background of the icon selection dialog also white icons that are set do not show in the button images windows. Please fix.
The icons are displayed as they are. I don’t think any of our icons are all white so you must be talking about a third party icon set. If so, you can make the icons any color you want by editing them, if they don't already come in multiple colors.
If the icon set is made from one big image grid then recoloring it should only take a few seconds with an image editing tool.
I think the original poster might be requesting something like Photoshop's checkerboard background in the icon preview pane so that icons that consist only of white and transparent are visible on preview.
Checkerboards make small icons hard to see IME, but we will be making that preview use a dark background if the UI is set to dark mode in the future, which should solve things unless viewing an icon set that’s inverted vs the current mode.
We could let icon sets specify a background for the preview, or have a button that toggles it from light to dark, I guess, but I’m not sure those are needed.