168354 - Mouse wheel scrolls the wrong window

Status: RESOLVED INVALID

(Core :: Widget: Win32, defect)

Description

[Richard Ekle]

The mouse wheel scrolling appears to be scrolling whatever window the mouse
pointer is currently over, rather than the window that contains the focus.

To Reproduce:
1. Open two Mozilla windows, that overlap each other.
2. Click to make the top window the active window.
3. Point to the bottom, non-active window with the mouse (do NOT click on it)
and scroll the mouse.  

You'll see that the bottom, non-active window is scrolling when you use the
mouse wheel rather than the top, active window.

This bug can also lead to some strange behavior if you have IFRAME windows
inside the current browser window.  For example, you start scrolling the main
web page until the IFRAME window happens to come under the mouse pointer.  THen
the IFRAME window starts to scroll and you can no longer scroll the main browser
window.

Comment 1

[Andreas Kunz]

Well, Opera behaves the same, IE 6 does not scroll at all.
I think one could argue if there is any better behaviour than what Mozilla does.
The IFRAME issue is not necessarily the same. There are bugs filed about
scrolling stopping when scrolling over plugin spaces.

Comment 2

[Robert Claypool]

Bug 301974 is related to this bug. When a Mozilla window is focused, any Mozilla
window scrolls when the mouse is over it. When any other window is focused,
Mozilla windows do no scroll. When Windows Explorer windows are focused they
scroll no matter where the mouse is. With Regedit the pane that has focus
scrolls no matter where the mouse is. From previous experience, this seems
pretty consistent behavior across most windows programs I have encountered.
Checking with IE6 indicates it IS an exception.

Comment 3

[Robert Claypool]

Does this issue contribute to ram bloat? It seems to me that the capture of the mouse necessary for this to occur may cause access to memory structures for the non-focused window that would be marked stale otherwise and paged to disk.

Comment 4

[Serge Gautherie (:sgautherie)]

Filter "spam" on "guifeatures-nobody-20080610".

Comment 5

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

-> INVA (or should be WONTFIX?)

This behavior was designed so. Gecko honors the cursor position for deciding which scrollable frame should be scrolled.

If you have some objections -- e.g., current behavior makes accessibility problem --, please reopen this bug with explaining them.

Note that the last paragraph problem was fixed by bug 312831.