multiple screens - mouse goes outside the screen and can't activate the launcher

[Dražen Lučanin]

Binary package hint: unity

When I have multiple screens of different resolutions connected, the mouse pointer can go outside of the screen in which case it can be very hard to "hit" the corner left corner and get the launcher to show.

Depending on whether the bigger screen is a bit above or bellow the smaller one, the mouse can disappear on the upper or lower edge of the screen and it's hard to hit the upper corner (and show the launcher) or the lower corner (make the launcher unfold to show all the icons on the bottom of the launcher).

This should probably either be fixed in the multiple screen management program so that the mouse can't go off the screen or in Unity to take into account the case in which the pointer can go beyond the screen above the upper left corner or below the lower left corner and make those areas also trigger the desired behaviour.

Also, I noticed on some occasions when I am using multiple screens that hitting the left edge doesn't make the launcher unfold around the icon on that height (or let me click at the icon), but I have to move the mouse a few pixels to the right first - as if the mouse pointer can go 1px outside of the screen to which the launcher isn't sensitive.

I am using Ubuntu 11.04, my screens are: a 15.4" 1600x1050 laptop and a 20" 1600x1200 Dell monitor, but I've noticed similar issues with other external monitors connected (23" 1920x1080 LG, for example).

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Desired resolution:

Patch the internals of the Xorg stack to remove the deadzones and solve this issue

[Alex Boardman (boardinary)]

I can also confirm this same behaviour using my 12.5 inch x220 thinkpad (1366x768) and my 1680x1050 monitor. The laptop uses intel graphics.

[Bilal Akhtar (bilalakhtar)]

Fixing such a bug would need design discussion. Marking needs-design.

[Alex Boardman (boardinary)]

I don't understand why it needs design discussion? It is just a bug that causes the mouse to be able to leave the viewable area at the top or bottom depending on screen setup.

[John Lea (johnlea)]

Is this bug is just requesting a fix to the issue where by the pointer can (in a specific multi-monitor configuration) actually leave the visible screen? If so no design input is required as this problem would be a purely technical bug.

I have removed ayatana-design from this bug.

[Bilal Akhtar (bilalakhtar)]

I should have been more clear on why I marked this needs-design.

This isn't a bug in Unity, its in the way X handles dual screens. Even in GNOME-Panel, you'll get a zone where you can move the mouse but it won't be on either screen. This zone is usually located to the top of the screen having a lower resolution than the other screen.

Now, fixing this in Unity, in the way mentioned in the bug report, would mean modifying Unity to make a barrier around the top of the BFB so that the mouse doesn't move over to the dead zone. Now, this would impact people using Unity with two monitors arranged vertically, as they won't be able to move the mouse over to the top screen from the bottom one through the BFB (they'll have to move the mouse over other parts of the panel instead).

So we need some design discussion on how this should be fixed. Either:
1) Don't fix this bug, leave it as it is (its not a major problem in any case).
2) Make a mouse barrier around the top edge of the BFB.

John?

[Bilal Akhtar (bilalakhtar)]

Also, since X doesn't give proper indications on which part of the screen is the dead zone, it'd be near-impossible to corden-off that zone.

[Dražen Lučanin (kermit666)]

Yes. Probably the healthiest solution would be to not have dead zones at all, but have the pointer enter another desktop whenever it leaves the present one, but that might require big rewrites in the multiple monitor handling code (I don't know how would it go with switching to different resolutions, scaling the pointer size etc.)

[John Lea (johnlea)]

I agree with Dražen Lučanin comment directly above, I think the correct fix is to remove the dead zones. Just having a barrier over the BFB seems like a very bad idea.

Bilal, what do you think?

[Bilal Akhtar (bilalakhtar)]

@John,

Not allowing dead zones to come up, would mean patching up the internals of the Xorg stack (dead zones are an issue with X, and isn't a Unity bug). The best we could do is make a barrier above the BFB, but that's a really bad idea.

I'm closing all Unity bug tasks, and opening a task for X so that the Ubuntu X-SWAT team can give its guidance on this bug.

[John Lea (johnlea)]

@ Bilal Akhtar,

Thanks for the reply, the Xorg stack fix is the appropriate response to this issue.