On Wednesday, 25 August 2021 14:22:39 BST Peter Humphrey wrote:
> On Wednesday, 25 August 2021 12:27:08 BST Neil Bothwick wrote:
> > On Wed, 25 Aug 2021 11:35:26 +0100, Peter Humphrey wrote:
> > > > > 	As the Firefox dir is all text files, I think, when you
> > > > > 
> > > > > blow it away and rebuild and get the correct behaviour, grab a
> > > > > copy. When the dodgy behaviour returns diff the copy, with the
> 
> good
> 
> > > > > behaviour, against the current dir, with the dodgy behaviour, and
> > > > > see what's changed. That may lead to an indication of what's being
> > > > > naughty.
> > > > 
> > > > Good idea. Thanks Andrew.
> > > 
> > > Just a small matter of 308 files to check.  :)
> > 
> > diff -r old/ new/ >lotsofstuff/txt :)
> :
> :)

I have observed something similar in three edge use cases.

1. When the browser is fighting against the window manager, or display 
environment, in the rendering of the application.  I recall this being a 
particularly annoying problem a few years back, with Chromium on Enlightenment 
DE.  From what I recall the problem was caused by Chromium's code taking over 
some window rendering functions, which conventionally was performed by the 
window manager.  Minimising and restoring the Chromium window was a workaround 
to fix this problem, until Chromium improved their code.

2. When an application window is running in a QEMU VM and the VM full desktop 
window itself is not maximised on the host.  The mouse events are 
geographically misaligned with the target.  After the guest desktop window is 
maximised the mouse becomes aligned and remains so even if the guest desktop 
window is resized thereafter.

3. On a particular system I discovered Firefox tabs and scroll bar disappear, 
or do not respond, when running on Plasma in Wayland.  Plasma in X11 plus 
Firefox works fine.

I haven't found a workaround for the Firefox problem on Wayland, perhaps an 
update will address this.