How to display the insert index when sorting manually (Tasks applet)

[Christian Mollekopf]

Hi,

while working on the improved sorting and grouping in the tasks applet

for the manual sorting in the tasks applet i wanted to show the insert index 
similar as it's done in the panel when sorting applets, so showing a spacer 
item where the task will be inserted.

unfortunately i noticed some problems with it and i'm not sure if it wouldn't 
be better to just display a vertical line between the tasks.

The first problem with the spacer is that if you drag a task over the taskbar, 
the whole thing starts to move. If you have one row thats okay and can be 
smoothened by using animations and  timers before showing the spacer. With 
several rows it's rather annoying because items at the end of the row jump to 
the beginning of the next row.

The second problem is a bit harder to explain.
Imagine a taskbar like this (S are sorting hitboxes and G are grouping 
hitboxes):

|SGGS|SGGS|SGGS|

 so as soon you drag a task over the S hitbox of an item the spacer is 
inserted:
|SGGS|SPAC|SGGS|SGGS|

If you drag your task now to the right because you actually want to group with 
item 2, the spacer dissapears and you mouse is immediatly over item 3 instead 
of two.

Therefore i suggest using a cursor like bar to display the insert index.

Regards,

Christian