Review Request: Workaround Taskbar ghost entries bug

[Alex Fiestas]

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http://git.reviewboard.kde.org/r/102779/
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Review request for Plasma and Aaron J. Seigo.


Description
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Well, as some of you may know I have been tracking down the ghost entries bug... this time I have NOT been able to fix the source of the problem but at least after some GDB at BDS I think I have a workaround.

A Ghost entry happens when a TaskItem is not either a startup or a task, in that case the code that "paints" the task doesn't know what to do but it reserve the space anyway.
Currently the code path is like this:
1-TaskGruopItem::itemAdded is called
2-It calles TaskGruopItem::createAbstractItem
3-createAbstractItem takes a GroupableItem and cast it either to a GroupItem, or LauncherItem or TaskItem depending on the ::itemTtype()

createAbstractItem is prepared to return 0 when an AbstractTaskItem can't be created, and even further WindowTaskItem::setTask is checking if the taskItem is not a startup or a task, the problem is that setTask returns void so we can't really know if the "setting" was succeed or not. In that case, an "empty" WindowTaskItem is returned, being it a ghost entry.

This workaround what does is check if the taskItem is valid, if it is not 0 is returned.

This is a workaround since, in theory a TaskItem should ALWAYS be either a startup or a task so we should find the root of the problem instead of adding yet another check. Is precisely this kind of checks that make all *tasks* stack a mess.


Diffs
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  plasma/desktop/applets/tasks/taskgroupitem.cpp eec27c2 

Diff: http://git.reviewboard.kde.org/r/102779/diff/diff


Testing
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I have been using the patch for 3 days playing around with activities and virtual desktops, so far so good.


Thanks,

Alex Fiestas

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