[Bug 366521] [NEW] VMWare fusion host + vmmouse driver generates drag events on any click

[John Dong]

Public bug reported:

Binary package hint: xserver-xorg-input-vmmouse

I'm noticing an issue using VMWare 2.0.2 as a host and Jaunty as a guest
that vmmouse likes to generate drag events overzealously. This is
apparent when:

(1) Clicking in a text field with the left mouse button sometimes
highlights a single character. This is extremely apparent in a gnome-
terminal, when clicking in a blank past-newline area selects the rest of
the line. Even if I raise my optical mouse off the table to the point
where I doubt the mouse itself is sending motion events.

(2) If I right click to bring up a context menu, often times it will
select the first item for me instantly.


Investigating with xev, when doing a single still mouseclick I see an event like
---
ButtonPress event, serial 30, synthetic NO, window 0x3000001,
    root 0xfc, subw 0x0, time 283641182, (79,109), root:(84,175),
    state 0x0, button 1, same_screen YES

MotionNotify event, serial 30, synthetic NO, window 0x3000001,
    root 0xfc, subw 0x0, time 283641766, (79,109), root:(84,175),
    state 0x100, is_hint 0, same_screen YES

ButtonRelease event, serial 30, synthetic NO, window 0x3000001,
    root 0xfc, subw 0x0, time 283641766, (79,109), root:(84,175),
    state 0x100, button 1, same_screen YES
---

The MotionNotify event is unusual; I don't see that with a physical
mouse or a non-vmmouse mouse, it seems to notify a motion to the same
spot.

This seems to cause many UI toolkits to mis-interpret what happens as a
miniscule drag.


To work around this issue, I played around with a quick hack in vmmouse.c to disallow a buttonpress event from triggering a motion event too, i.e. src/vmmouse.c line 495:
---
if ((dx || dy) && (truebuttons == pMse->lastButtons))
---


This SIGNIFICANTLY helps the case with a standstill mouse, but I STILL the slightest motion of the mouse while clicking will trigger a small MotionNotify event and cause the same behavior. I find this to be an unrealistic emulation of a mouse -- with no physical Linux system and mouse combination have I had to work so hard at keeping the mouse still while clicking.


It might be a good idea to guard against miniscule motion events while dragging.

** Affects: xserver-xorg-input-vmmouse (Ubuntu)
     Importance: Undecided
         Status: New

-- 
VMWare fusion host + vmmouse driver generates drag events on any click
https://bugs.launchpad.net/bugs/366521
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