Good afternoon, I am new to the list so please excuse me for jumping in, however I develop software for use with touch screens. I have experienced the exact same problem but with Windows 7 (I know, wrong platform). However the root cause was with the device itself either missing event signals or them being out of order. From your email you imply you've only looked at the output of X, rather than what is coming from the device via USB. Regards Phil <div class="gmail_quote">On 12 October 2012 14:38, Thierry Reding <<a href="mailto:thierry.reding@avionic-design.de" target="_blank">thierry.reding@avionic-design.de</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi, I've been seeing a very strange issue. Originally this was observed when using a browser with an onscreen keyboard. It would sometimes happen that the keys on the keyboard would get stuck and be repeatedly sent. While trying to debug this, I came across a reliable way to reproduce it using xwininfo. Basically I would run xwininfo and select the onscreen keyboard. This would immediately result in the key being pressed and not receiving a release event. Using other keys on the onscreen keyboard would make them pressed as well, but never released either, resulting in repeated keypresses received by the browser. It seems like X for some reason believes that the press event is actually a release and vice- versa. In order to find out what exactly was going on, I fired up xev with the window XID as reported by xwininfo. This would indeed show the repeated key events sent to the onscreen keyboard's window. Strangely enough, if xev is started without an existing window XID, generating touch events in that window seems to "fix" the issue. The keyboard can be used reliably again. Furthermore, when running xwininfo and selecting the onscreen keyboard, a second call to xwininfo would fail, saying it cannot grab the mouse. This issue can be reliably reproduced independent of the onscreen keyboard and works with any X window. So opening an xterm for instance, then running xwininfo and selecting xterm will cause any subsequent calls to xwininfo to fail. Running xev and generating touch events in its window again fixes things. It seems like the X server doesn't properly release the grab and gets the touch down and up events mixed up. Note that all of this only happens when using a touchscreen device. Performing the same tests using a regular USB mouse to select the X window for xwininfo doesn't show the same behaviour. I'm using version 1.13 of the X server and xf86-input-evdev 2.7.3. Can anybody else reproduce this? If you need any more information I'd be happy to provide it. Thierry _______________________________________________ <a href="mailto:xorg-devel@lists.x.org">xorg-devel@lists.x.org</a>: X.Org development Archives: <a href="http://lists.x.org/archives/xorg-devel" target="_blank">http://lists.x.org/archives/xorg-devel</a> Info: <a href="http://lists.x.org/mailman/listinfo/xorg-devel" target="_blank">http://lists.x.org/mailman/listinfo/xorg-devel</a> </blockquote></div>