65013 - disabling clearing of damaged areas

Status: VERIFIED INVALID

(Core :: XUL, defect)

Description

[Tom]

Mozilla has (probably deliberately) chosen to disable clearing
of damaged window areas by the X server.  This may seem to make
it easier to reduce flashing in applications when areas are 
damaged, but it has serious consequences when using Mozilla over
slower or high latency connections, as well as when Mozilla
itself is less than immediately responsive.

If a toolkit disables automatic clearing of damaged window areas
by the server, it risks that graphical components from other windows
remain displayed as part of the Mozilla windows, including title
bars and contents of other windows.  This is visually
very confusing and seriously affects usability because users
may get confused about what is a real GUI component and what
is merely junk bits that haven't been cleared out of Mozilla
window.  Furthermore, this decision by Mozilla doesn't just
affect the usability of Mozilla but of the whole desktop on
which it appears.

The decision to have the X server automatically clear damaged
areas is a fundamental part of the X window system and has
been there nearly since the beginning.  A well-behaved application
should set the background color to a reasonable value (e.g., the
HTML page background) and let the X server clear damaged areas.

Since clearing by the X server is almost instantaneous, the
appearance is that damaged areas simply revert to the background
color when they become visible.  This is no worse than to have
them acquire the bits of, say, an opaque window that is dragged
across them and does not cause any additional visible redraw.

Many X toolkits use this behavior with no visible artifacts,
and I believe Mozilla should as well.

Comment 1

[timeless]

toolkit

Comment 2

[Peter Trudelle]

->bryner for triage

Comment 3

[Brian Ryner (not reading)]

I've noticed that Mozilla does this also, and it drives me nuts :)

Comment 4

[Christopher Blizzard (:blizzard)]

We should make mozilla faster.  We should also have it fill in rects that were
exposed but not drawn by an html view.  roc's new view manager does this.  I'd
rather avoid two paints, thanks.

Comment 5

[Brian Ryner (not reading)]

perhaps roc's view manager is supposed to do this, but it doesn't.  Filed bug
65107 on that.

per blizzard's comments, closing out this bug as INVALID.

Comment 6

[Chad Austin]

Lots of verifications.

If I had to test stuff, it was on Win2K, build id 2001052404.