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Re: BUG [ 100250 ] highlight menu item sometimes fails

From: Richard Frith-Macdonald
Subject: Re: BUG [ 100250 ] highlight menu item sometimes fails
Date: Sun, 3 Feb 2002 07:30:30 +0000

On Sunday, February 3, 2002, at 12:29 AM, Fred Kiefer wrote:

I had a deeper look into the problem behind the bug 100250 and found
that it is created by a view that is moved to another window, while the
view needs display. In that specific constellation the method [NSView
setNeedsDisplayInRect:] does not work correct. As the whole area of the
view is already invalid the new window (and the super views) is not
marked as needing display.
There are multiple ways to resolve this problem and I am not sure which
is the best. Currently I would prefer to flag the view when moving it to
a new superview first as not to need display and than as needing
display. That way the invalid area is first cleared and than everything
works as expected. This would require changes to the methods
[addSubview:], [replaceSubview:with:] and
Another way to do it would be to flag a view as not needing display in
the [removeFromSuperview:] and
[removeFromSuperviewWithoutNeedingDisplay:] methods. Or to try to handle
this case in [setNeedsDisplayInRect:], but this would need a lot of
extra checks.

When a view is added to another view, it gets marked as needing display
anyway.  The problem is that if it is already marked as needing display,
the propagation of that information up the view hierarchy is optimised
So what's needed is to unmark it when removing it so that the marking
as needing display upon addition can operate correctly.  This can be done
with one call to -setNeedDisplay: in the -removeSubview: method, since all
removal of views uses that method.

There is another smaller problem here in the method [NSWindow
orderWindow:relativeTo:]. Here the sending of needs display calls from
the runloops to the window is only started when the window does not need
display. This seem to be the wrong way round.

Yes ... a bug.

I added your fixes.

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