[vbox-dev] UseMouse is skipping mouse clicks intermittently

Michael Thayer michael.thayer at oracle.com
Mon Oct 8 01:46:58 PDT 2012

Hello Vic,

On 10/06/2012 01:50 PM, Vic Lee wrote:
> I am not sure if anyone is aware of the issue, but for quite a while I
> notice that virtualbox is obviously skipping my mouse clicks. Depending
> on whether I have guest mouse driver installed or not, whether I connect
> to console or through RDP, the skip rate may be different but not solved.
> I spent some time debugging from source and I am able to identify the
> issue is in function usbHidMousePutEventAbs() in UsbMouse.cpp. There is
> a call to usbHidQueueRemoveHead (line 801) which will return NULL
> whenever my click is skipped. The problem here is that if the button
> state is not being changed, it will be ok to skip mouse events; but if
> pThs->PtrDelta.btn != fButtonStates, the event should not be skipped,
> but must be queued until available. Otherwise either mouse press or
> release event will not be reported to the host and is quite annoying.
> usbHidMousePutEvent() function should be the same as well.
> UsbKbd.cpp, however, is properly queuing pending key events, thus I
> never experience missed keys. Any idea to improve UsbMouse?
The maintainer of the USB pointing device emulation code (Michal, CC-ed) 
is taking a look at it and can see the problem, but is a bit surprised 
that you are the first person to notice it.  Would you be able to 
provide more information about how you are using VirtualBox which might 
give us a hint?



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