In Evolution the "Tasks" is not really a task
list. It is a rather a
ToDo list, which is difficult to organize when you
have more than 5-7
items, and it is really a mess when there are more
than 10.

I propose to implement a task composition paradigm
similar to MrProject
tasks.
A task typically consists of several sub-tasks,
each sub-task may
contain sub-sub-tasks and so on, building a tree
of sub-tasks. The depth
of a hierarchy must be up to the user. The tasks
with start-date and
due-date in the past must be highlighted similarly
to a new email in the
folder hierarchy.

Now the tasks can be ordered only by date,
completeness and summary, and
I have to introduce the prefix (numbers or
letters) for the task summary
to force the ordering. And this prefix solution is
not good since the
task list is dynamic. 
Another useful feature could be the user-definable
task ordering (at a
hierarchy level), pretty much the same as the song
ordering in XMMS play
list.