user32:clipboard CLIPBRDWNDCLASS interference (Radeon, others)

[Francois Gouget]

This is the Windows side of the issue.

user32:clipboard sometimes fails like this:

clipboard.c:54: 0cc8: Starting open_and_empty_clipboard_thread hWnd=00010010
clipboard.c:55: 0cc8: OpenClipboard(00010010) = 1 (open=00010010 own=00000000)
# the thread terminates which implicitly calls CloseClipboard()
# so the clipboard should be unopened

clipboard.c:429: Test failed: wrong open window 00670304
# but it is actually opened

It turns out 670304 is actually a CLIPBRDWNDCLASS window created by 
RadeonSettings.exe.

CLIPBRDWNDCLASS is (usually) a class registered by ole32.

Why does a graphics driver (or associated tools) need to access the 
clipboard? It may actually be some background thing done by the QT5 
framework in which case (based on the issue below) upgrading to a driver 
using QT5 > 5.12 may help.

https://github.com/Sigil-Ebook/Sigil/issues/401
https://code.qt.io/cgit/qt/qtbase.git/tree/src/plugins/platforms/windows/qwindowsclipboard.cpp


But it turns out Radeon is not the only one using Ole's clipboard and if 
I try enough times I can also get failures on Nvidia. The w7u VM also 
has the telltale class but I have not seen failures there.

cw-rx460-win81 (Radeon 19.11.3)
clipboard.c:2248: 00670304 CLIPBRDWNDCLASS 0190 '' [C:\Program Files\AMD\CNext\CNext\RadeonSettings.exe]
                  hwnd     class           pid  text executable path

cw-rx460-win2009 (Radeon 21.3.2)
clipboard.c:2246: 00040054 CLIPBRDWNDCLASS 0c1c '' [C:\Windows\explorer.exe]
clipboard.c:2246: 0004002C CLIPBRDWNDCLASS 1850 '' [C:\Windows\System32\svchost.exe]
clipboard.c:2246: 00030056 CLIPBRDWNDCLASS 1850 '' [C:\Windows\System32\svchost.exe]

cw-gtx460-win2009 (Game Ready Driver 391.35)
clipboard.c:2247: 000201B2 CLIPBRDWNDCLASS 1c68 '' [C:\Windows\System32\svchost.exe]
clipboard.c:2247: 00010230 CLIPBRDWNDCLASS 1c68 '' [C:\Windows\System32\svchost.exe]

w7u
clipboard.c:2246: 000100EA CLIPBRDWNDCLASS 05f0 '' [C:\Windows\Explorer.EXE]
clipboard.c:2246: 00010052 CLIPBRDWNDCLASS 05f0 '' [C:\Windows\Explorer.EXE]


In any case, guided by the failure patterns I first tried to upgrade the 
Radeon driver. That helped on cw-rx460-1909 (21.3.2) but the latest 
drivers either won't install on older Windows versions (the infamous 
error 184), or crash regularly (even when left alone, and frequently 
enough during the tests to trigger a Windows reboot). So at least 
Windows 10 1507 and Windows 8.1 are stuck with 19.11.3 and its 
RadeonSettings.exe (I did not try the intermediate Windows versions).

Furthermore, while it would likely greatly reduce the failure rate we'd 
probably still get failures once in a while, likely at a rate so low it 
would cause TestBot false positives. Just like on Nvidia actually (see 
the cw-gtx560-1809-32 and cw-gtx560-1909-32 lines).

-- 
Francois Gouget <fgouget at codeweavers.com>