When I left-click on the empty space above/below the scrollbar (you know, the "PgUp/PdDn" area), it works normally as pageup or pagedown -- except when after the movement the sliding box is below the mouse. When it happens, the pageup/pagedown action is "stuck", and it goes on until it reaches the top/bottom of the document. Clicking on the pageup/down area again fixes it (unless after this click the mouse ends up again above the sliding box -- then the same mess happens again in the opposite direction. This is very common on short pages, and is annoying since the keyboard shortcuts don't work in some builds in a random fashion -- some builds have the PgUp/PgDn keys working, others don't). Also, middle-clicking in the sliding box makes the mouse get "stuck" -- it moves the page up and down even after you released the button and left the scrollbar area. Clicking on the page background with the _left_ button is the only way to unstuck the movement. Current build here is 1999121108, but I've seen this weird behavior for some builds (since about M10 IIRC -- I don't follow the builds closely).
This bug has been reproduced on all platforms with the 1999121208 builds. To repro get any page that's a couple screenfuls long or shrink your window. With the thumb at the top of the window click and hold in the middle of the scroll area. The thumb (and pae scroll) will race past the moue until it reaches the bottom of the window.
targetting p4 m14
This only happens in trees. Hyatt are you setting the current pos to be greater than the max pos?
*** This bug has been marked as a duplicate of 18193 ***
I don't think this is actually a duplicate of 18193, unless it's a duplicate at a technical level I don't understand (likely), but it does seem to be resolved at least for the most part, and at least for the win32 builds.
Ok, are you seeing this in scrollbars other than scrollbars attached to tree views? Try bringing up www.mozilla.org and scrolling it. Do you see this problem. If the answer is yes, reopen the bug and give it back to evaughan. If the answer is no, that you only see it in tree scrollbars, then it is a dup, since it only happens because the scrollbar gets out of whack on trees, and that's what the other bug refers to.
Confirmed that this is still happening with browser window GFX scrollbars on NT, for ordinary HTML pages. This looks a *lot* more like bug 22512, "Clicking just below scrollbar thumb moves thumb to bottom", blocker, M14, dogfood, not one of yours at all, hyatt. REOPENing to change DUP.
*** This bug has been marked as a duplicate of 22512 ***
VERIFIED dupe. there are two slightly different behaviors that are i believe similar but unrelated. they both are mentioned in this bug. One issue is dealt with in bug 22512 the other in bug 26914