That is firefox. But it does it on dialog boxes too if there are checkboxes or the like. So it's most noticeable when browsing with firefox, but other similar issues occur within windows and other applications as well.
And actually I've never heard of the Pale Moon browser, hehee, so nope.
So to kind of recap:
anytime I use any skin for object desktop toggle boxes and radial buttons and those sort of things no longer are visible.
Here is another example from firefox:
this is with skinned:
And here is after unloading the skin:
Another example is on this page itself. When I have a skin running, I can't see the post button, I just see the text. When skin is disabled, I can see the button.