Hi peppyy:
I might be describing a different issue, but:
I may, to use an old canine expression, be "barking up the wrong tree" but
I have noticed in recent Palemoon usage, when I move my mouse to, for example,
a login in "click on area", an all black "window" drops down.
I've found that if I just move my mouse pointer slowly over the "black window",
I can now read each of, are they called, "suggestions" and click on the one I want.
(if my "list of suggestions" is long, there will be a "slider" to allow
scrolling the "black area" list.)
(I think that months or even years ago, such little window's items could be viewed
immediately without the effort with my mouse. Perhaps this was a
"security" feature introduced to prevent someone looking over your shoulder from
immediately reading the items in your list.)
If this is your issue too, maybe my comment may give a clue about both
what this behavior is really called and what could be changed.
Hope this helps.