Windows client highlighting text in gedit window can disable clipboard.

[alas]

Still testing the clipboard a little with Windows client 3.0-r23707, against 3.0-r23689 server on Fedora 30, I noticed some odd warning messages (possibly expected) when pasting into a gedit window.

2019-09-05 12:40:13,220 client is requesting an unknown target: 'GTK_TEXT_BUFFER_CONTENTS'
2019-09-05 12:40:13,221  valid targets: text/plain, text/plain;charset=utf-8, UTF8_STRING
2019-09-05 12:40:13,221  dropping the request

Some permutation (maybe highlighting something, then highlighting something else and copying, then pasting into gedit?) was giving a slightly different warning.

2019-09-04 13:08:34,136 Warning: CLIPBOARD selection request for 'UTF8_STRING' timed out
2019-09-04 13:08:34,137  request 18 at time=0

And at some point in the testing I also triggered something client side, but I'm not sure what it was (traceback, might be easy to find and address?).

Traceback (most recent call last):
  File "./xpra/client/gtk_base/gtk_client_window_base.py", line 1985, in do_unma
p_event
NotImplementedError: virtual method Gtk.Widget.unmap_event not implemented

While trying to pin down all these details though, I discovered I can easily trigger a warning about more than 30 clipboard requests per second simply by highlighting a small portion of text in a gedit window in the session... and if I don't notice the warning quickly enough (3 seconds I guess), then I can (and did) disable the clipboard entirely.

2019-09-05 12:47:31,436 Warning: more than 30 clipboard requests per second!
2019-09-05 12:47:31,456 Warning: more than 30 clipboard requests per second!
2019-09-05 12:47:35,399 Warning: PRIMARY selection request for 'UTF8_STRING' timed out
2019-09-05 12:47:35,399  request 170 at time=0
2019-09-05 12:47:57,836 Warning: more than 30 clipboard requests per second!
...
2019-09-05 12:47:59,570 Warning: more than 30 clipboard requests per second!
2019-09-05 12:47:59,590 Warning: more than 30 clipboard requests per second!
2019-09-05 12:47:59,602 Warning: more than 30 clipboard requests per second!
2019-09-05 12:47:59,622 Warning: more than 30 clipboard requests per second!
2019-09-05 12:47:59,622  limit sustained for more than 3 seconds,
2019-09-05 12:47:59,622  the clipboard is now disabled
2019-09-05 12:47:59,629 client   2 @05.256 clipboard toggled to off by the server, reason given:
2019-09-05 12:47:59,634 client   2 @05.259  more than 30 clipboard requests per second!

And, while I can apparently use the menu to 'double disable' the clipboard, there's no mechanism to re-enable it.

2019-09-05 12:49:59,182 client   2 @04.804 unknown string message: 0xc241L / 0x52 / 0x46
2019-09-05 12:49:59,184 client   2 @04.806 unknown string message: 0xc241L / 0x50 / 0x0
2019-09-05 12:50:11,133 client   2 @16.753 clipboard synchronization direction changed to: disabled
2019-09-05 12:50:30,166 client   2 @35.784 server clipboard synchronization changed to CLIPBOARD selection
2019-09-05 12:50:30,166 Warning: unexpected clipboard packet
2019-09-05 12:50:30,167  clipboard is disabled for 731790b2e835c5605eb26c9fd4c4a1b1c0268390
2019-09-05 12:50:30,171 client   2 @35.788 server clipboard synchronization changed to CLIPBOARD selection
2019-09-05 12:50:30,173 Warning: unexpected clipboard packet
2019-09-05 12:50:30,174  clipboard is disabled for 731790b2e835c5605eb26c9fd4c4a1b1c0268390

But, in the process of trying to re-enable, I triggered the client side error again (maybe that helps?)

2019-09-05 12:50:14,284 clipboard synchronization direction changed to: disabled

2019-09-05 12:50:33,317 server clipboard synchronization changed to CLIPBOARD se
lection
2019-09-05 12:50:33,320 server clipboard synchronization changed to CLIPBOARD se
lection
Traceback (most recent call last):
  File "./xpra/client/gtk_base/gtk_client_window_base.py", line 1985, in do_unma
p_event
NotImplementedError: virtual method Gtk.Widget.unmap_event not implemented

(now to get back to the point of #1844...)

[Antoine Martin]

client is requesting an unknown target: 'GTK_TEXT_BUFFER_CONTENTS'

GTK applications do that: they request targets that don't exist...
So we drop them and log a message.

Warning: CLIPBOARD selection request for 'UTF8_STRING' timed out

Timeouts should be rare, and they should be handled gracefully enough.
Let's re-open if this causes problems.

NotImplementedError: virtual method Gtk.Widget.unmap_event not implemented

That's a weird one. The window class should always handle unmap events.
I've tried to reproduce it but I just cannot hit it. (unmap is usually triggered when the window is iconified or moved to another desktop)
From now on, we'll log it with better details at error level: r23722.
In any case, I don't think this is too much of a problem.

Warning: more than 30 clipboard requests per second!
limit sustained for more than 3 seconds,
the clipboard is now disabled

We no longer disable the clipboard when getting many requests: r23723.
Though we should handle this better and just rate limit them: #2404.

And, while I can apparently use the menu to 'double disable' the clipboard, there's no mechanism to re-enable it.

There is, but it is well hidden. Because the clipboard is disabled server-side, that's where you would have needed to re-enable it, using the clipboard-direction control command, or its dbus equivallent. (ie: change from "disabled" to "both")

[migration script]

this ticket has been moved to: ​https://github.com/Xpra-org/xpra/issues/2403