I normally have a lot of tabs open in the browser at one time, which normally doesn't cause any problems.

Occasionally, though, the page will have fully rendered, the scroll bar is at the top of its track on the right, but placing the the mouse pointer on the scroll bar does not allow me to get control of it (and using the arrow at the bottom of the scroll bar doesn't work either). This seems to happen to me in both Firefox and Chrome, both latest versions. There is normally no load on the CPU, and while my memory usage can be high (especially with Chrome), I still usually have >25% left.

I fear that this is one of those "for your own good" features, to prevent scrolling down a page that may still have elements loading and/or a stuck script, but I'm wondering whether or not there is a setting in Firefox or Chrome (or perhaps Windows in general) that will allow the scroll bar to be "released" even though the browser may be busy?

It may be "2002" of me, but I wouldn't mind being able to scroll along gradually, even if the page hasn't had time to fully render all of the images, etc., yet.

Does such an advanced setting exist "under the hood"?