Instead of filling the whole row with selection color, only fill behind
the text. This gives a snugger, more focused appearance.
For embedders that want the entire row to get filled with the selection
color when selected, they can opt in to the old behavior by calling
TreeView::set_should_fill_selected_rows(). This is used by Profiler.
This code was confusing two different versions of scroll_into_view that
were getting mixed up due to member function shadowing.
Adding an "override" to the subclass declaration exposed the problem.
With this fixed, we no longer lose our scroll position wildly when
using the mouse to select TreeView items.
Views now have a cursor index (retrievable via cursor_index()) which
is separate from the selection.
Until now, we've been using the first entry in the selection as
"the cursor", which gets messy whenever you want to select more than
one index in the model.
When setting the cursor, the selection is implicitly updated as well
to maintain the old behavior (for the most part.)
Going forward, this will make it much easier to implement things like
shift-select (extend selection from cursor) and such. :^)
A view can now be told to move its cursor in one of multiple directions
as specified by the CursorMovement enum.
View subclasses can override move_cursor(CursorMovement) to implement
their own cursor behavior. By default, AbstractView::move_cursor() is
a no-op.
This patch improves code sharing between TableView and TreeView. :^)
This is really just a workaround to keep SystemMonitor's process table
working right wrt selection retention during resorts (while also doing
full index invalidation on things like ProfileViewer inversion.)
It's starting to feel like the model abstraction is not super great
and we'll need a better approach if we want to actually build some more
dynamic functionality into our views.
