[winswitch] Pressing alt sometimes generates space characters, and dragging window is unreliable

[Joakim Ziegler]

I've installed Xpra 4.0.1 on the server (Ubuntu 20.04) and Xpra 3.0.9 on
the client (Centos 7.7.1908), and I'm using it to run Chrome, we're
currently in testing, and everything seems to be working fine, apart from
two fairly minor problems:

We use Chrome in large part for accessing Google Docs, and we noticed a
strange problem. Sometimes when pressing Alt-Tab to switch windows, the
current cell in Google Sheets would blank, that is, the contents would be
replaced by one or more space characters. At first we thought this was
something that happens when switching windows, but it turns out, it's
something that happens irregularly when pressing Alt.

If you open Google Docs and move around between cells with contents in them
by clicking the mouse, and then press Alt, some times (one out of five,
maybe), pressing Alt will generate space key presses, which blanks out the
cells. This only happens after having used the mouse to click on the cells,
and what's stranger, even if it doesn't happen every time, when it does
happen, the number of space key presses generated seems to be proportional
to the number of times you've pressed Alt before this happens, so if it
happens after trying to provoke it three times, you'll get three space
characters.

Is this a known bug? Might it be a result of using 3.0.9 on the client and
4.0.1 on the server? I'm happy to generate a formal bug report, but I
wanted to know if this was a known problem that might be solved by an
upgrade first.

Secondly, and this is less important, when dragging the Chrome window by
the title bar, the first time you drag, it works fine, but if you release
the mouse button and then immediately try to drag the window again, it
won't move. It'll move again on the third attempt, then not on the fourth,
and so on. I'm also wondering if this is a known problem, and/or related to
using 3.0.9 on the client.

-- 
Joakim Ziegler  -  Supervisor de postproducción  -  Terminal
joakim at terminalmx.com   -   044 55 2971 8514   -   5264 0864