Launcher - a spread can accidentally be triggered during the 'dragging and dropping behind the Launcher' interaction

Bug Description

To reproduce try dragging a file behind the launcher over a launcher icon that has 2 or more windows open and is a valid drop target. Frequently a spread will be accidentally triggered.

Desired Resolution:
- Block the triggering of a spread when the user is dragging a file and their cursor is positioned on the far left pixel of the screen.

This bug was fixed in the package unity - 4.18.0-0ubuntu1

---------------
unity (4.18.0-0ubuntu1) oneiric; urgency=low

* New upstream release.
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(LP: #845732)
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(LP: #765749)
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(LP: #802527)
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screen (LP: #802651)
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(LP: #836325)
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is set to true (LP: #847967)
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(LP: #853807)
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(LP: #854740)
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- Dragging a launcher icon makes it squashed (LP: #855761)
- unable to unminimize gedit windows where more than one window where one
has a dialog open (LP: #856030)
- (oneiric) alt-tab UX doesn't work well on multi-monitor (LP: #855364)
- Launcher shows on the primary monitor instead of the left most monitor
(LP: #857668)
- Keynav - pressing down key causes launcher items to jump up and down
(LP: #858469)
- Windows creep cross the screen with ALT+TAB (LP: #722830)
- Minimize animation flickr when for maximized apps (LP: #737125)
- All unity windows are invisible (panel, launcher, dash) (LP: #745996)
- Dash "See 97 more results" has ~1 second of latency (LP: #731158)
- Windows cannot be dragged down from panel if banshee closed to sound
menu (LP: #781215)
- no menu bar on top, compositing bug? (LP: #806358)
- Launcher - a spread can accidentally be triggered during the 'dragging
and dropping behind the Launcher' interaction (LP: #832988)
- Impossible to navigate between panel menus when the mouse cursor is over
the panel (LP: #834065)
- Pressing alt on maximized window does show menu but not window controls
(LP: #836274)
- Application name drawn under Dash controls when window opens under Dash
(LP: #838176)
- Start ...

Re-opened as it is impossible to test due to regression with bug https://bugs.launchpad.net/ayatana-design/+bug/607796

It should not be set to confirmed IMHO. The spread on drag has been disabled in Ubuntu 11.10, but if we enable it now, we no longer have this bug. So it should be Fix Released or at least Invalid.