Very strange problem with input events

Peter Hutterer peter.hutterer at
Wed Jun 13 20:52:28 PDT 2012

On Wed, Jun 13, 2012 at 09:02:52PM +0200, Cedric Sodhi wrote:
> Unfortunally, I lack a better or just more precise description of my
> problem. I get strange behaviour all throughout X, everywhere clicks are
> involved.
> One thing I think I had already mentioned is that my touchscreen, which
> runs evdev does work properly everywhere, but there are no regular
> events generated - only XI events.

this can only be a client issue. I can't tell you which client from here
though. The drivers and the server don't deal with core vs XI events until
very late. There' internal events and then based on the client selection
that internal event structure is converted to the wire event and sent.

So if you don't see core events, the clients haven't registered for it, or
clients have otherwise registered for XI events and take precedence over

> Also, many applications strangely misbehave in a way that other people
> cannot possibly reproduce. Unrelated to the touchscreen, that is. Using
> an ordinary mouse with evdev.
> Two examples:
> Tint2 (the panel) had me "drag" window-icons ("tasks") on the taskbar,
> when I clicked them, as if I had held the mouse button down. I was able
> to "fix" that by a minor change in the code of tint2, but as no one else
> is getting any such behaviour I assume I did not really fix the bug but
> only found some solution to somewhich, which fails elsewhere. I was not
> able to track the logic which is supposed to run, though.
> Second example, Midori (the browser). When I right click a hyperlink and
> subsequently left click an entry in the context menu, the context menu
> disappears (as it should) and I'm suddenly "dragging" the link upon
> which I clicked.
> Similar things happen everywhere else, too.
> I'm not even sure where to start looking. I wish I could get a
> suggestion from you, what to do.

options are trying an older X servers and bisecting from a good one if you
can find one.

or look at the protocol with xscope to see the actual events sent on the
wire (you can also use systemtap/dtrace for that but it's less pretty).

For the link issue, I'd check the evtest output of the touchscreen to see if
the actual device data makes sense.


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